UK raises terror alert for transport hubs

The U.K. has raised its terror alert level for transport hubs, with Scotland Yard saying “an attack is highly likely,” according to reports.

While the national assessment has remained unchanged at “severe,” the second highest level, for the past year, the security-threat level at subway stations and airports in Britain was raised from "substantial" to "severe" on Wednesday night as a precautionary measure, media outlets quoted sources as saying.

According to The New York Times, Scotland Yard said the current national level meant that “an attack is highly likely,” and promised to “police accordingly and use a range of covert and overt tactics which remain under constant review.”

Meanwhile, the British Transport Police department was not commenting on reports that it had increased security at subway stations and airports after new information emerged about the possibility of an attack being planned in or near London, CNN reported.

"We don't have armed officers in our stations," the department said Friday. "We have been briefed about how to respond to a Mumbai-style gun over the last few months. We don't comment on deployment of officers but I can tell you that we haven't canceled any leave."

However, The Associated Press reported that police were on patrol at major hubs like St. Pancras and King's Cross train stations in what seemed to be an exercise in high visibility policing aimed at reassuring the public.

The action was not connected to terrorism arrests last month in Stoke, Cardiff and London, CNN reported.

Britain's move comes after France and Germany increased security after warning of a heightened threat of terrorist attack.

In October, the U.S. State Department advised American citizens living or traveling in Europe to be wary amid reports that terrorists were planning a "Mumbai-style" attack on a European city.

More than 170 people were killed in a 2008 gun attack on multiple targets in the Indian city of Mumbai.