Just days before he is due to leave Iraq, the Coalition Provisional Authority (search) administrator Paul Bremer is facing new accusations that he is hindering, rather than helping, the oil-for-food investigation.

Rep. Christopher Shays (search ), R-Conn., wrote Bremer a letter in May requesting answers to a series of questions about Bremer's handling of the oil-for-food investigation. Bremer recently responded to that letter and, according to Shays, there are many questions left unanswered.

“The response is incomplete," Shays said in a statement Wednesday. "There is still an insufficient accounting of relevant documents in custody. Several questions and requests are simply unanswered."

• Raw Data: Shays' Letter to Bremer | Bremer's Response (pdfs)

Shays said that contracts with the accounting firms Ernst & Young and KPMG, a memorandum of understanding between the Iraq Board of Supreme Audit (search) and the U.N. Independent Inquiry Committee, and an inventory of oil-for-food documents in the CPA's possession have not been supplied.

“The Subcommittee will continue to pursue these matters because documents and information in the hands of U.S. government agencies, like the CPA, are critical to finding the truth about what went so very wrong with the U.N. oil-for-food program," Shays said.

In his letter to Shays, Bremer says that the CPA isn't even the organization that Shays should be contacting with oil-for-food-related questions.

While the CPA "shares the Subcommittee's interest in this serious matter," Bremer wrote, "the Iraqi Board of Supreme Audit is best prepared to conduct such an investigation, in view of its legal status as a separate and independent public agency ... and the fact that it will continue to function as Iraq's highest public audit organization following the transfer of governance authority to the Iraqi interim government."

In addition to the questioning from Shays, Bremer is also under pressure from the Senate Permanent Subcommittee on Investigations, which has sent a formal letter to him requesting that he hand over oil-for-food documents.

And in another sign that U.S. authorities are beginning to move more aggressively, the subcommittee chairman Sen. Norm Coleman, R-Minn., has served a subpoena on BNP Paribas, the bank that handled billions of dollars of oil-for-food money.

David Kelley, U.S. attorney for the southern district of New York, is also seeking information on the oil-for-food program, serving subpoenas on Chevron Texaco, Exxon Mobil and Valero Energy Corp., to find out more about Iraqi oil purchases.

A three-member panel led by Paul Volcker (search), the former U.S. Federal Reserve chairman, is investigating the oil-for-food scandal. The panel does not have subpoena authority and will rely instead on voluntary cooperation from governments, U.N. staff, members of Saddam Hussein's former government and current Iraqi leaders.

The panel says it has evidence that dozens of people, including top U.N. officials, took kickbacks from the $67 billion oil-for-food program.

The General Accounting Office (search), the U.S. Congress' investigative arm, estimated in March that the Iraqi government pocketed $5.7 billion by smuggling oil to its neighbors and $4.4 billion by extracting kickbacks on otherwise legitimate contracts.

Under the oil-for-food program, which began in December 1996 and officially ended in November 2003, Saddam's government could sell unlimited quantities of oil provided the money went primarily to buy humanitarian goods and toward reparations to 1991 Gulf War victims.

FOX News' Jonathan Hunt contributed to this report.