Jonathan Evans, in a rare interaction with the media, said the terrorists, who attacked Mumbai in November, had indirect links with Britain.

"We have looked at individuals' communications, where they have been and so on and found they have got connections with most countries including the UK, but not of national security significance," he said.

But the MI5 director general warned that Mumbai could become a model for future terrorist attacks in the same ‘iconic’ way as September 11 strikes in the US.

"If the method used in Mumbai of using firearms in public places becomes adopted as a model, it changes our most likely scenarios," he added.

Evans said that scores of British Muslims were still travelling to terror training camps in Afghanistan and Pakistan every year. Others are travelling to lawless areas of Somalia.

The main threats to Britain come from al-Qaeda's core in Pakistan and their ‘assets in this country’, he said.