In a recent meeting with lawmakers, CIA Director Leon Panetta acknowledged that the agency had misled Congress about "significant actions" the agency took between 2001 and this week, House Democrats charge.

It's not clear what the CIA misled lawmakers about, however.

A number of House Democrats are now asking Panetta to correct his earlier assertion that the CIA does not lie to Congress, a charge he made to rebut Speaker Nancy Pelosi's (D-Calif.) claim that she was misled by the agency.

"Recently you testified that you have determined that top CIA officials have concealed significant actions from all Members of Congress, and misled Members for a number of years from 2001 to this week," the House Democrats wrote in a letter to Panetta. "This is similar to other deceptions of which we are aware from other recent periods."

In May, responding to Pelosi's charges, Panetta denied that the CIA lies to lawmakers.

"Let me be clear: It is not our policy or practice to mislead Congress," he said. "This is against our laws and values."

Meanwhile, Rep. Silvestre Reyes (D-Tex.), the chairman of the House Intelligence Committee, is charging that the CIA "affirmatively lied" to Congress.

"This committee has been misled, has not been provided full and complete notifications, and [in at least one case] was affirmatively lied to," Reyes wrote in a letter to House leaders on Tuesday.

Reyes did not explain what the CIA had lied about, however.