A senior military officer and a senior Defense Department official confirmed at a hastily called Pentagon briefing on Monday, after news reports had disclosed the existence of the expanded intelligence operations, that small teams of civilian intelligence specialists were being created to work with Special Operations forces and other troops worldwide on secret missions, including counterterrorism operations.

The officials said the teams had been formally established in the fiscal year 2005 defense budget using existing authority to replace ad hoc defense intelligence units that had been deployed to Iraq and Afghanistan for more than two years.

In interviews, however, members of Congress from both parties questioned whether the secret missions being carried out by the units might amount to covert actions - a legal definition for missions in which the United States government denies any role and that can be undertaken only by presidential directive and with formal Congressional notification.

Some members also said the House and Senate intelligence committees had not been fully informed about the new approach, even though they oversee the Defense Intelligence Agency.

"To cut out Congress and set up an under-the-radar capability which Congress doesn’t know about is not O.K.," Representative Jane Harman of California, the top Democrat on the House intelligence committee, said in an interview.

But Senator John W. Warner, a Virginia Republican who heads the Armed Services Committee, said in a statement that the intelligence teams were "vital to our national security interests" and that their existence was included in Pentagon budget documents that the committee reviewed and approved.

The Pentagon officials said Congress had been informed about the teams during the budget discussions late last year, but they said the names of the units had been changed during the budget process, to Strategic Support Teams from Human Augmentation Teams, possibly explaining the confusion.

The teams are financed with Defense Department money in the National Foreign Intelligence Program, a portion of the Pentagon budget administered by the director of central intelligence, the officials said. But they declined to give exact budget figures.

Officials said the units would have about 10 members each, consisting of case officers, linguists, interrogators and other specialists from the Defense Human Intelligence Service, a branch of the Defense Intelligence Agency. While the missions they would take up would be secret, the intelligence units would not use covert methods like false identities or nationalities, the senior military officer said.

The briefing was organized late Monday in response to an article in The Washington Post on Sunday and an article in The New York Times on Monday. The Pentagon spokesman, Lawrence Di Rita, said officials giving the briefing on Monday must stay unidentified because intelligence matters were being discussed.

Stephen A. Cambone, the under secretary of defense for intelligence, and Vice Adm. Lowell Jacoby, the head of the Defense Intelligence Agency, were sent to Capitol Hill on Monday afternoon to answer a flurry of questions from lawmakers of both parties.

In general, Democrats and Republicans expressed support for the idea of assigning intelligence officers from the D.I.A. to work alongside Special Operations forces in wartime situations like the ones in Iran and Afghanistan. They said the Pentagon could also contribute much needed additional resources to the task of recruiting spies, traditionally the domain of the Central Intelligence Agency.