Four men have been arrested, including one at Gatwick airport, as part of investigations into people travelling to Syria in support of alleged terrorist activity.

A 33-year-old man was arrested at Gatwick airport on Wednesday afternoon as he attempted to take a flight out of the UK. Three other men, aged 18, 31 and 22, were arrested at separate addresses in east London in dawn raids on Thursday.

A Metropolitan police spokesman said: "They are all in custody at a south London police station where they will be interviewed by officers from the MPS's counter-terrorism command."

Searches are continuing at three residential addresses in east London.

The arrests are linked to an investigation in which two men were arrested and charged over the kidnapping of two photographers – Briton John Cantlie and his Dutch colleague Jeroen Orelemans – in Syria in July.

Jubayer Chowdhury, 24, was arrested by counter-terrorism officers at Heathrow airport in November after arriving on a flight from Bahrain. Shajul Islam, 26, a trainee NHS doctor, was arrested in October as he arrived back in the UK with his wife and one-year-old daughter on a flight from Egypt, and is accused of being part of an extremist group that held the two photographers.