The head of MI5 has warned that Islamic State aspires to commit “devastating” and “more complex” attacks in Europe after losing territory in the Middle East.
Andrew Parker told European security chiefs in Berlin the group required international focus “for years”.
He revealed 12 terror attacks have been stopped in the UK since the Westminster attack in 2017.
He condemned Russia for the “reckless” poisoning of the Skripals in Salisbury.
Mr Parker warned the threat posed by IS, which he referred to as Daesh, would persist, driven by its “murderous ideology”.
“Whilst Daesh has now lost its false caliphate in its strongholds in Syria and Iraq, tackling the group as a movement will require sustained international focus for years to come,” he said.
“As I speak today, they are seeking to regroup, and the threat seems likely to persist.”
Security and intelligence expert Phil Ingram told the BBC there is competition between different extremist groups.
“Islamic State have been blamed for [attacks] – that’s upset a lot of al-Qaeda-affiliated groups who want to get back into high-level, sophisticated attacks like they did with the 9/11 attacks, because they see Islamic State getting the media limelight,” he said.