A 36-year-old man has been arrested on suspicion of preparing terrorist acts, police confirmed in a statement.
Counter-terror police detained the man as he arrived at London’s Heathrow Airport on Thursday, Scotland Yard said.
He is now in custody at a west London police station.
The nationality of the man is unclear.
He was arrested on suspicion of the preparation of terrorist acts, contrary to section 5 of the Terrorism Act 2006.
According to the MI5, the current threat level for international terrorism in the UK is SEVERE.
A severe threat means that an attack is highly likely.
Threat levels are designed to give a broad indication of the likelihood of a terrorist attack.
- LOW means an attack is unlikely.
- MODERATE means an attack is possible, but not likely
- SUBSTANTIAL means an attack is a strong possibility
- SEVERE means an attack is highly likely
- CRITICAL means an attack is expected imminently