WASHINGTON (CNN) -- The CIA has sent a report to the U.S. Justice Department indicating classified information may have been leaked to The Washington Post for its recent story about secret prisons run by the spy agency, according to U.S. officials.The newspaper reported last week that the CIA was holding top suspected al Qaeda terrorists at undisclosed prisons in eastern Europe and other locations.The Justice Department refused to confirm or deny a referral was made.The action by the CIA general counsel was taken immediately after the Washington Post article was published, an official said.It is similar to one taken when covert officer Valerie Plame's name was made public in an article written by a syndicated columnist.By law, when there is the possibility that classified information has been leaked, the CIA is required to inform the Justice Department, which generally launches an investigation into the matter.Earlier Tuesday, Republican congressional leaders asked for an investigation into the matter, and Sen. Trent Lott of Mississippi suggested his own GOP colleagues could be to blame for the possible leak.Sen. Bill Frist of Tennessee, the Senate majority leader, and Rep. Dennis Hastert of Illinois, the House speaker, asked the chairmen of the House and Senate intelligence committees to look into the report, saying the disclosure could damage national security."If accurate, such an egregious disclosure could have long-term and far-reaching damaging and dangerous consequences, and will imperil our efforts to protect the American people and our homeland from terrorist attacks," they wrote in a letter requesting the investigation.Lott told reporters the information in the Post story was the same as that given to Republican senators in a closed-door briefing by Vice President Dick Cheney last week."Every word that was said in there went right to the newspaper," he said. "We can't keep our mouths shut."Lott, a former Senate majority leader who was pushed out in 2002, suggested the information was passed along by a senator to a staff member.He said the investigation Frist and Hastert want may result in an ethics probe of a Senate member.Citing U.S. officials and those from other governments familiar with the arrangement, the Post reported Wednesday that top al Qaeda suspects were being held for questioning "at a Soviet-era compound in Eastern Europe" and other locations around the world.Critics said the arrangement suggests U.S. agents are engaged in activities that would be illegal under American law.Top U.S. officials would not confirm or deny the report, but insisted all prisoners are being treated humanely. President Bush said flatly Monday, "We do not torture."A Washington Post spokesman said the paper had no comment on the possibility of an investigation.The leak probe request was announced as top administration officials battled a Senate-approved measure that explicitly bars "cruel, inhuman, or degrading treatment or punishment" of prisoners in U.S. custody.The White House has threatened to veto a $440 billion Pentagon spending bill if it includes that measure, which is backed by Republican Sen. John McCain of Arizona -- who as a prisoner of war during Vietnam was tortured by his North Vietnamese captors.And it came a day after Democrats called for an independent investigation into the treatment of prisoners in American custody.House Minority Leader Nancy Pelosi urged GOP leaders to initiate a broader investigation -- one that would include the 2003 leak of Valerie Plame's identity and the faulty intelligence used to argue for the invasion of Iraq."There is plenty to investigate about the Bush administration's use and misuse of intelligence," the California Democrat said in a written statement. "The American people deserve the truth."Democratic Sen. Harry Reid of Nevada, the Senate minority leader, told CNN the GOP announcement was "just for show."And a senior Democratic aide called it a way for Republicans to divert attention from the grand jury probe into the exposure of Plame, whose husband had publicly challenged a key element of the Bush administration's case for war.That disclosure led to the October 28 indictment of Lewis "Scooter" Libby, who resigned as Cheney chief of staff.Libby was charged with obstruction of justice, perjury and making false statements to federal agents investigating who revealed Plame's identity to reporters.CNN's David Ensor, Pam Benson, Ed Henry and Ted Barrett contributed to this report.