Federal air marshals will expand their work beyond airplanes, launching counterterror surveillance at train stations and other mass-transit facilities in a test program this week, according to internal federal documents.

Teams of undercover air marshals and uniformed law enforcement officers will fan out to bus and train stations, ferries and mass-transit facilities across the country to "counter potential criminal terrorist activity in all modes of transportation," according to documents from the Transportation Security Administration.

The documents showed the teams — known as "Visible Intermodal Protection and Response" or "Viper" teams — will take positions in public areas along Amtrak's Northeast Corridor and California rail lines; ferries in Washington state; and mass transit systems in Atlanta, Philadelphia and Baltimore.

The story was first reported on the Washington Post Web site Tuesday night.

Teams patrolling the Washington, D.C., Metro subway system will consist of two air marshals, one TSA bomb-sniffing-canine team, one or two transportation security inspectors, one local law enforcement officer and one other TSA employee.

Federal officials said there was no new intelligence indicating that terrorists are interested in targeting public transportation, the Post said.

The Transportation Security Administration is instead trying to expand the role of air marshals, who have been eager to conduct surveillance activities beyond aircraft, and provide a beefed-up law-enforcement presence in bus, train and other public-transit stations over the busy holiday period.

"We think this is a very good approach to test our tools and quickly deploy resources in the event of a situation or a threat," the Post quoted Federal Air Marshal Service spokesman David Adams as saying. "It shows we could be at any of these places."

Some members of the team will be obvious to the traveling public and will wear jackets bearing the TSA name on the back. Others will be plainclothes air marshals scanning the crowds for suspicious individuals.

It is unclear how many Viper teams will be on patrol through the New Year's holiday, but air-marshal officials confirm that they will be at seven locations across the country.