Reports of any changes in staffing of federal air marshals aboard U.S. airlines are flat-out wrong, a Department of Homeland Security (search) spokesman told Fox News Wednesday.

Spokesman Brian Roehrkasse said no current plan exists, nor has any plan been discussed, to lower the number of air marshals.

News of possible cuts began circulating Wednesday after the Transportation Security Administration (search) reported that it wants Congress to cut $104 million from the air marshal program to help offset a $900 million budget shortfall. It was unclear how the possible cuts could affect air marshal jobs.

"When we are faced with more priorities than we have funding to support, we have to go through a process of trying to address the most urgent needs," TSA spokesman Robert Johnson said.

But a Homeland Security official told Fox News that no cuts to the air marshal program have been approved by either Asa Hutchinson, the undersecretary in charge of that department, or by Homeland Security Secretary Tom Ridge.

Added Rep. Harold Rogers, R-Ky., chairman of the House Appropriations Subcommittee on Homeland Security: "The Federal Air Marshal program is absolutely critical to fighting terrorism and keeping the flying public safe. Given new warnings from DHS about possible hijacking attempts, it is foolish to even consider cutting back the number of air marshals on commercial flights.

In fact, the official said, DHS will expand the air marshal program in the face of the latest threat information about Al Qaeda (search) and the possibility the terror group may be planning another Sept. 11-like attack by the end of the summer.

A warning issued by DHS earlier this week alerting the airline industry to possible Al Qaeda threats says: "The extremists may plan to identify flights that transited the target country, so that the hijackers would not need visas for those countries."

The terror plot could involve the use of five-man teams, each of which would attempt to seize control of a commercial aircraft either shortly after takeoff or shortly before landing at a chosen airport, the advisory said. DHS stressed that airlines are responsible for abiding by strong security procedures at airports, particularly for those traveling without a visa.

The Sept. 11 attacks were carried out by three five-man teams and a four-man squad of hijackers, U.S. officials believe.

DHS is canvassing for individuals with previous air marshal experience to sub into the program, the official said. Air marshal assignments will be made based on the current threat information, the official added, including the possibility of hijackings and increasing screening of certain overseas passengers.

A TSA official said the agency sent a directive to U.S. airlines on Monday telling them to immediately begin more intensive screening of travelers flying out of a foreign airport into the United States, then connecting to another foreign destination.

Those affected are non-U.S. citizens who do not have U.S. visas. They previously have been allowed to stay in secure areas while passing through U.S. airports but have not been subjected to more intensive screening because they aren't staying in the country.

President Bush noted the hijacking warning during a White House news conference Wednesday and said U.S. officials are talking to foreign governments about it.

"There are still Al Qaeda remnants that have designs on America. The threat is a real threat," he said. "We obviously don't have specific data. We don't know when, where, what. ... I'm confident that we will thwart their attempts."

Officials said the credibility of the threat was still being evaluated. But they noted there was no precise information on when or where such an attack could take place.

The national terrorist threat level remained at yellow, signifying an elevated risk of attacks. The five-level, color-coded system was last raised to orange, or high risk, for 11 days in May. Officials said they did not plan to raise it to reflect the possibility of suicide hijackings.

DHS placed a statement on its Web site saying the advisory was transmitted after U.S. intelligence-gatherers "received information that Al Qaeda continues to be interested in using the commercial aviation system in the United States and abroad to further their cause."

In response to the advisory, the State Department on Tuesday revised an existing caution for American travelers to reflect the perceived hijacking threat.

"Terrorist actions may include, but are not limited to, suicide operations, hijackings, bombings or kidnappings. These may also involve commercial aircraft," the revised statement said.

Fox News' Catherine Herridge and the Associated Press contributed to this report.