UK's new anti-terror chief warns of indiscriminate attacks

The Islamic State terror group is plotting "indiscriminate attacks on innocent civilians" in UK cities on a scale similar to the one executed by the IRA in 1970s, Britain's new anti-terrorism chief Max Hill has warned.

The recently appointed Independent Reviewer of Terrorism Legislation said hundreds of British jihadists who are returning from war zones pose a level of threat to the UK not seen since the Irish Republican Army (IRA) bombings in the 1970s.

Hill said the Islamic State was planning "indiscriminate attacks on innocent civilians on a scale similar to those perpetrated by the IRA 40 years ago".

"I think the intensity and the potential frequency of the serious plot planning with a view to indiscriminate attacks on innocent civilians of whatever race or colour in metropolitan areas - represents an enormous ongoing risk that none of us can ignore," Hill was quoted as saying by 'The Sunday Telegraph'.

"So I think that there is undoubtedly significant ongoing risk which is at least as great as the threat to London in the 1970s when the IRA were active on the mainland," he said.

More than 50 people were killed by IRA attacks in Britain during the 1970s.

Hill, who successfully prosecuted the failed would-be bombers in 2005, praised the UK's intelligence services' "truly remarkable" success rate for foiling plots since the 2005 London bombings."

It's an enormous concern that large numbers - we know this means at least hundreds of British citizens who have left this country in order to fight - are now returning or may be about to return," he said.