Democratic lawmakers said Tuesday that the CIA misled and/or lied to Congress about its intelligence programs at least five times since 2001, including one previously alleged instance in which the agency failed to disclose to top members of the House and Senate intelligence committees that the CIA tortured war on terror detainees.

Moreover, a top intelligence official revealed during a House Intelligence Committee hearing that there were other "minor instances" where Congress was not notified about significant covert activities.

Speaking to reporters immediately after the hearing, Rep. Jan Schakowsky (D-Illinois) said the CIA's failure to disclose details about its use of so-called "enhanced interrogation techniques" is a "symptom of a larger disease."

Schakowsky revealed that, in addition to withholding information from lawmakers about torture, the CIA lied or misled Congress about the shooting down of an airplane over Peru in 2001 carrying American missionaries, the destruction of torture tapes and a top secret assassination program aimed at targeting leaders of al-Qaeda. She would not reveal details of what the fifth case was. A 2008 CIA inspector general's report had already concluded that the agency lied to Congress about the Peru incident.

Schakowsky and Rep. Anna Eshoo (D-California), who chair House Intelligence subcommittees, led Tuesday's hearing. They are also leading the investigation into the CIA's alleged failure to fully inform Congress about its covert activities. The National Security Act of 1947 says the CIA must keep Congress "fully and currently informed" via classified briefings about its intelligence activities.

Schakowsky said Tuesday the intelligence panel is in the process of "reviewing several instances where the executive branch may have violated the requirements that are in the National Security Act."

The investigation was launched in July, weeks after CIA Director Leon Panetta told members of Congress during a classified briefing that the agency withheld details from Congress about the assassination program. Panetta reportedly told lawmakers that former Vice President Dick Cheney instructed the CIA to conceal the counterterrorism program from lawmakers.

Committee Chairman Silvestre Reyes and other top lawmakers on the intelligence panel said in a letter released that month that CIA officials "affirmatively lied" to Congress and misinformed the committee on numerous occasions about other intelligence matters.

During Tuesday's hearing, Robert Litt, general counsel for the Office of Director of National Intelligence (DNI), testified that an internal review launched last summer by DNI Director Dennis Blair determined that Congress was not briefed in a timely manner or given details about other classified intelligence programs. Litt said lawmakers have since been brought fully up to date.

"There have been many instances where we've come to a committee hearing, after having read in the paper of something that should have been notified to us, where it's followed up my mea culpas by the intelligence community," Schakowsky said during the hearing. "And examples where the committee actually has been lied to. You can understand that the committee has felt very frustrated that the executive branch has not notified us of intelligence activity."

Wendy Morigi, an agency spokeswoman, downplayed the issue and characterized it as a minor oversight.

Blair instructed the directors of all US intelligence agencies October 13 that they must notify Congress within 14 days after the start of significant intelligence activities, the first time a formal deadline has been imposed.

Questions about whether the CIA had fully informed Congress about its covert activities was called into question earlier this year when House Speaker Nancy Pelosi alleged that the CIA misled her in classified briefings in September 2002 about the Bush administration's torture of "war on terror" detainees. Pelosi was ranking member of the House Intelligence Committee at the time.

In claiming that the CIA misled her and other members of Congress, Pelosi said the CIA briefers obscured the fact that the agency already had begun subjecting prisoners to the near drowning of waterboarding and was using other torture techniques.

"We were told explicitly that waterboarding was not being used," Pelosi told reporters during a press conference last May. The CIA "misled us all the time."

Pelosi made these claims weeks after the Justice Department released declassified legal memos written by former Office of Legal Counsel attorneys John Yoo, Jay Bybee and Steven Bradbury. The memos gave CIA interrogators the green light to subject war on terror detainees to brutal torture methods.

Some Democrats reacted to the memos by calling on the Justice Department to launch a probe into the Bush administration's torture program. But some Republicans, notably, Rep. Pete Hoekstra, (R-Michigan), the ranking minority member of the Intelligence Committee accused Democrats of feigning outrage and claimed that Pelosi and other Democrats in the "Gang of Eight" were fully briefed by the CIA about the use of torture, specifically waterboarding.

Following Pelosi's claims, the CIA turned over a document to Hoekstra that contained the dates and a summary of the briefings given to a select group of Congressional leaders, including Pelosi and former Senate Intelligence Committee Chairman Bob Graham (D-Florida) about "enhanced interrogation techniques ... employed" against "high-value" detainees.

Hoekstra and other Republicans seized upon the document, claiming it proved that Democrats were complicit in the Bush administration's torture program since they did not raise objections to the specific interrogation methods when briefed.

But the briefing document did not specifically state that the CIA briefed Pelosi and other members of Congress that detainees were subjected to waterboarding or any other torture technique. Moreover, the document was rife with errors. Three of the four dates in which the CIA said it had briefed Graham do not match his records.

"When I asked the CIA when was I briefed, they gave me four dates, two in April and two in September of '02," Graham said. "On three of the four occasions, when I consulted my schedule and my notes, it was clear that no briefing had taken place, and the CIA eventually concurred in that. So their record-keeping is a little bit suspect."

Hoekstra demanded Pelosi apologize to the CIA for accusing the agency of lying. Ironically, Hoekstra was the lawmaker who accused the CIA of lying to Congress about the Peru incident, though he has since distanced himself from the allegations.

Schakowsky said Tuesday that in the months ahead she "will lead the investigation through a document request and review; open hearings on the history and status of congressional notifications; closed fact-finding hearings to drill down into the circumstances and details of prior notification failures; and interviews with individuals of interest."

She intends to produce a report at the conclusion of the investigation detailing the committee's findings.

"It is my plan that the investigation report will contain recommendations for reforms to the congressional notification procedures," Schakowsky said. "Through the deliberate and careful examination of past notification failures, the Committee can better identify the source of the problem. The Committee and the Congress then has the opportunity to correct the law and make revisions to ensure that we can fulfill our oversight mission."