The Treasury Department (search) rejected a request from senators Tuesday and refused to release a classified list of Saudi individuals or organizations suspected of financing terrorist groups.

A Treasury spokesman, Rob Nichols, said a department official misspoke when he told senators last week the list was unclassified, which would mean it was not restricted information.

"The last thing we want to do is tip off terrorists that we are on to them," Nichols said. "We don't want to disrupt ongoing investigations, covert actions or potential law enforcement actions."

Administration attorneys are reviewing the degree to which the classified information can be provided or shared with Congress in closed session, said a government official, speaking on condition of anonymity.

The refusal to release the list marks the second time in two weeks that the Bush administration has rejected requests by senators to declassify information about Saudi ties to terrorists.

Democratic and Republican senators have urged the Bush administration to release at least part of a 28-page section of the congressional report on the Sept. 11, 2001, attacks that deal with foreign support for the hijackers. People who have seen the section said it examines interactions between Saudi businessmen and the royal family that may have aided the hijackers.

The Saudi government strongly denies helping terrorists in any way and says it is working closely with the United States to combat them.

Secretary of State Colin Powell (search) said Saudi Arabia has been "especially aggressive" in responding to U.S. terrorism requests for help. In an interview broadcast Monday to Arab countries, Powell told U.S.-financed Radio Sawa the Saudis are finding caches of weapons and ammunition that were intended for terror attacks in Saudi Arabia and elsewhere.

But, Powell said, "There are always more things that all of us can do." Specifically, Powell said, "We still have issues with respect to financing, and how money gets to charitable organizations."

At a Governmental Affairs Committee hearing last week, senators pressed the Treasury Department's Richard Newcomb about whether foreign relations interests caused the department to avoid action against groups suspected of financing terrorists. Newcomb is director of Treasury's Office of Foreign Assets Control (search), which notifies U.S. banks when they are to block assets of suspected terror financiers.

Sen. Carl Levin, D-Mich., asked whether the department's list of groups suspected of helping terror organizations was classified. When Newcomb said it was not, Levin requested the list. Sen. Mark Pryor, D-Ark., later repeated the request.

Nichols, the Treasury spokesman, said Tuesday Newcomb made an inadvertent error in saying the list was not classified.

The Governmental Affairs chairwoman, Sen. Susan Collins, R-Maine, was waiting for a formal response from Treasury before commenting, said a spokeswoman, Elissa Canlas. Levin's office issued a statement that he was also awaiting a response.

Nichols would not speculate about Treasury's response if senators were to subpoena the information.