Police presence at airports, rail and road transport hubs was beefed up across London after a fresh terror alert was sounded in the city, weeks after security officials foiled two serious terrorist plots.

Extra police was deployed at various transport hubs in the city and all police leave cancelled after intelligence was received that terrorist could be planning fresh attacks, British media reports on Friday said quoting security officials.

Security was beefed up at London’s Heathrow airport and the Luton airport and at all major railway stations as reports said that terrorist could be preparing to target transport hubs in the city, The Daily Telegraph reported.

The British police have kept the overall threat at the second highest level “severe” which means that an attack is highly likely.

Sky news quoting Scotland Yard officials said members of the emergency service have been briefed about how to respond to Mumbai style-attack.

A security source said there was no “imminent” threat and the overall threat level had not changed but there was activity from one of a “handful” of extremist cells that cause concern at any time, leading to an adjustment in policing levels.

He said intelligence intercepts were not clear whether the terrorist were planning suicide bomb attacks of Mumbai-style shootings or a combination of both.