A second man has been arrested after counter-terrorism police stopped a man from boarding a plane to Turkey.
A 37-year-old man was arrested at Stansted Airport on Tuesday night on suspicion he planned to travel to Syria.
On Thursday a second man, aged 64, was arrested at a business address in north London, the Metropolitan Police said.
Both men, who have not been identified, are being held at a south London police station on suspicion of preparing for acts of terrorism.
The arrests are linked to travel to Syria and are not connected to the Manchester Arena attack, Scotland Yard said.
A warrant to detain the first man for further questioning was granted on Thursday.
Officers have also searched a further residential address in north London.