LONDON (REUTERS) - Two men from Birmingham have been arrested on suspicion of terrorism offences relating to activities in Syria, police said on Monday.

The men, both aged 21, were detained at Heathrow Airport On Monday afternoon after arriving back in Britain on a flight from Istanbul.

They are believed to have travelled to Syria last May, the West Midlands Counter Terrorism Unit said in a statement.

"We took action this afternoon in order to ensure we can properly understand what activities these men have been engaged in whilst in Syria, not because they posed any imminent threat to the public," said Unit head, Detective Chief Supt Kenny Bell.

No further details were immediately available.