Two men from Birmingham were arrested at Heathrow airport on Thursday (February 16) on suspicion of a terrorism offence.
West Midlands police said in a statement that the pair, aged 30 and 66, were detained at the airport under Schedule 7 of the Terrorism Act 2000.
They had been scheduled to board a plane out of the UK.
An address in Birmingham is due to be searched, added the police.
The statement said: “They have been arrested under section 5 of the Terrorism Act 2006 on suspicion of the commission, preparation and instigation of terrorism.”
The men have been transported to a police station in the West Midlands to be questioned.