London: A terror attack in the UK is "almost inevitable" in the coming months as the scale of terrorist activity has increased, security chiefs have warned.
Ministers are being updated daily about security and have been told by officials of a "step change" in the terror threat since the rise of the Islamic State and its call for self-starter attacks in the West after airstrikes in Syria, The Times reported.
"The scale of terrorist activity is so great that an attack is 'almost inevitable' in the coming months," the report said citing that this was the warning given by security chiefs to senior ministers.
MI5 and Scotland Yard believe they have stopped three plots in London in the past four months, two of them after urgent raids as suspects were allegedly poised to strike.
There was intense security for Remembrance Sunday yesterday, especially at the Cenotaph in Whitehall, London, where a large number of armed police were deployed, the report said.
Four men aged between 19 and 27 were still being questioned by police after arrests on Thursday and Friday during raids in west London and High Wycombe, Buckinghamshire.
The arrests came after intelligence was received that a terror attack using knives or other bladed weapons was in the final stages of planning.
Last month five men were charged in connection with planning a terrorist gun attack on a Metropolitan police officer and accused of having sworn an oath of allegiance to Islamic State (ISIS).
There were unconfirmed reports during the weekend that Abu Bakr al-Baghdadi, leader of ISIS, was wounded or killed in an air attack on a convoy. US Central Command said warplanes had targeted a "gathering of ISIS leaders".
Security officials are concerned that after several years in which they have had a stable intelligence picture of Britain's most dangerous extremists, they are dealing with new, more volatile, groups radicalised by events in Syria, the report said.
Of the estimated 600 British jihadists, about half have not been on the intelligence radar before, it said.
Some 300 are thought to have returned from the conflict zone and security agencies are trying to keep track of them.
A source was quoted in the report as talking about an increased threat because the murder of Fusilier Lee Rigby in Woolwich last year had taught terrorists that instead of elaborate al-Qaeda bomb plots, "they only need a kitchen knife and a mobile phone to carry out a high-impact attack".
However, General Sir Nicholas Houghton, head of the armed forces, said despite the threat Britons should not alter the way they lived their lives. "In an absolutely unreserved way I would say we have just got to keep continuing our normal life," he was quoted as saying by BBC.