Updated

The integrity of the probe into the Oil-for-Food program is at stake and lives may be in jeopardy if sensitive information regarding details of the investigation is leaked, Paul Volcker (search) said Friday.

Volcker, the man picked by U.N. Secretary-General Kofi Annan (search) to lead the investigation, publicly responded to recent congressional efforts to subpoena a former senior investigator on the Independent Inquiry Committee who thinks the panel has been too soft on Annan in its investigation.

The former investigator, Robert Parton (search), has also provided Congress with documents from the probe. In his remarks, Volcker asked Congress to return those records, which may contain information potentially harmful to Annan, sources have told FOX News.

Rep. Henry J. Hyde, R-Ill., however, refused to return the documents. Hyde, chairman of the House International Relations Committee, said he appreciated the gravity of Volcker's concerns, but that his committee is obligated to continue its own investigation.

"I consider Mr. Parton to be an honorable and courageous man who responded to a Congressional subpoena as any citizen must," said Hyde.

The evidence Parton provided to lawmakers includes audiotapes of interviews conducted with Annan, FOX News has learned. Sources had previously said that the evidence shows inconsistencies in the story Annan told investigators about his knowledge of his son Kojo's work for Cotecna, a company that won a lucrative Oil-for-Food contract.

Volcker said Friday that Congress has to restrain itself from requiring certain acts and information from current or former IIC members as it conducts hearings into Oil-for-Food (search).

"It is essential that it also protect the integrity and the confidentiality of the independent investigating committee," Volcker told reporters in New York, saying the probe involved "highly sensitive matters."

"Lives of certain witnesses are at stake," he added. "We're not playing games here, we are dealing, and let me just emphasize this, in some cases, with lives."

In a later question-and-answer session, Volcker did not elaborate too much on who may be threatened if too much information about who has cooperated is publicized, saying, "I couldn't tell you specifically who was threatening witnesses."

But he said: "We have had several amounts of cooperation from Iraq. You might understand there is concern from certain families … I do not limit that concern to Iraqis."

Rep. Chris Shays (search), R-Conn., chairman of the House Government Reform's Subcommittee on National Security, Emerging Threats and International Relations, issued a subpoena to Parton on Thursday. Parton on Wednesday night handed over documents relating to the investigation after he was issued a subpoena by another panel, the House International Relations Committee, on April 29.

"He [Parton] did decide to leave his work because he didn't agree with the findings of the report" released by the IIC in March, Shays told FOX News on Friday.

Parton and another IIC investigator, Miranda Duncan (search), left the panel headed by Paul Volcker (search) in mid-April. They accused the IIC of downplaying Annan's role in the scandal in an interim report released by the panel last March.

"The whole reason why the Volcker report was taking place was to bring confidence to the U.N. ... we would learn the good, the bad and the ugly. The bottom line is, we don't really have confidence in that report," Shays said.

Shays is requesting documents and other information relevant to the probe of the $64 billion program and has called on Parton to testify before his committee "to help augment the public record on matters too long shrouded in secrecy."

Volcker: Give Us Back Our Documents

Volcker, who is standing by his statement that the former IIC staffers should have diplomatic immunity, on Friday said three things should be done.

One, Parton could be released from his IIC confidentiality obligation limited to the specific purpose of giving a public statement about his views on the part of the report in question which deals with Annan. Two, the congressional committees should withdraw their subpoenas challenging immunities and privileges "inherent" in the United Nations and the IIC.

"Immunity's long accepted by all member nations of all international institutions, including the United States," Volcker said.

And third, IIC files that may contain confidential interviews and other information should be "promptly returned to the IIC, which is, in fact, the rightful owner."

"This is critical to the committee's work ... they [witnesses] have placed their trust in our confidentiality," Volcker added.

Shays said his panel tried to work with the IIC on ways, short of a subpoena, to evaluate the information Parton can provide about "key pieces of evidence regarding U.N. contracting." Neither the IIC nor the United Nations should stonewall the effort, he warned.

"I think Mr. Volcker ... should just let this gentleman speak to Congress," Shays told FOX News. "Mr. Volcker believes, basically, all the evidence was presented in the report. They just disagree on the conclusion of that evidence."

Click here to read Shays' letter to Volcker (pdf file).

A source close to Parton defended him and told FOX News on Friday: "Mr Parton is a professional and an honorable man who is acting reluctantly under compulsion of a congressional subpoena."

Lawmakers: Immunity Out

As senior investigative counsel, Parton was responsible for investigations into the procurement of companies under the Oil-for-Food program and he was the lead investigator on issues pertaining to allegations of impropriety relating to Kofi and Kojo Annan (search). Duncan worked on Parton's team.

Shays said immunity should be out of the question, since fighting over such "legalese" would not help restore confidence in the world body.

"We just want transparency, we're used to it in the United States. We have freedom of information, we don't have that in the U.N.," he said. "There will be no faith in the U.N. until all the facts are out ... everyone is cooperating, and people aren't cooperating."

Hyde has directed his own investigators to examine documents given to them by Parton this week.

"It is my hope and expectation that neither the United Nations nor the independent inquiry will attempt to sanction Mr. Parton for complying with a lawful subpoena," the Illinois Republican said.

The boxes handed over by Parton are believed to contain information damaging to the secretary-general because, as sources told FOX News, they describe inconsistencies in the story Annan told investigators about a conflict of interest involving Kojo Annan and Cotecna (search), the Swiss company that employed Kojo Annan and which won one of the most lucrative Oil-for-Food contracts.

Volcker wrote a letter to Parton's lawyer, Lanny Davis (search), on Thursday as well as to Shays, saying that turning over any investigation-related documents violated confidentiality agreements.

Click here to read Volcker's letter to Parton's lawyer (pdf file).

Click here to read Volcker's letter to Shays (pdf file).

"I do not have the feeling that the congressional committees ... are out to hamper our investigation," Volcker told reporters Friday. "They may do it inadvertently but that's not the purpose. I do think that as our investigation proceeds, there are people — and I'm not talking about committee chairmen — who would like to see us go away."

Legal Tangles

Davis had written to Volcker telling him that the House International Relations Committee instructed him and Parton to not tell the IIC or the United Nations about the subpoena issued on April 29 until Parton complied. That compliance occurred on Wednesday night.

Click here to read Davis' correspondence (pdf file).

Volcker responded in writing to Davis on Thursday, saying the IIC and U.N. did in fact answer Davis' questions but that the lawyer "chose to ignore" that direction, calling him "disingenuous."

On Friday, Volcker took another shot at Davis, saying that it's only alleged that Hyde's House International Relations Committee told Parton not to tell the U.N. or the IIC about the subpoena.

"Such instruction, with the threat of contempt of Congress, if in fact imposed, is unlawful," Volcker said.

Davis said in a statement that the dispute was one between Volcker, the United Nations and Congress.

"Let's be clear on two facts. Mr. Parton provided information to Congress only because it compelled him to do so by subpoena. And, despite his repeated requests for guidance made to the IIC and the U.N. over several days in the only manner consistent with Congress's instructions, the IIC and the UN never directed Mr. Parton to defy a Congressional subpoena," Davis said.

But Volcker said he spoke to Hyde on Friday afternoon and the chairman assured the IIC chief that neither he nor his staff instructed Parton or Davis to keep the subpoena a secret.

So far, Volcker's panel has released two interim reports that say the program suffered from mismanagement and raise questions about the role of Kojo Annan. A final report is expected to be released this summer.

FOX News' Jonathan Hunt and Per Carlson contributed to this report.