Two men who were arrested by officers from the Met's Counter Terrorism Command at Birmingham Airport have been released without charge.
The men, aged 40 and 29, and both UK nationals, were arrested after disembarking a flight from Istanbul, Turkey on Thursday.
The 40-year-old was arrested on suspicion of being concerned in the commission, preparation or instigation of acts of terrorism under section 41 of the Terrorism Act 2000.
The 29-year-old was arrested on suspicion of belonging to a proscribed organisation, which is an offence under section 11 of the Terrorism Act 2000.
A warrant of further detention was granted for both men, which was due to expire on Wednesday, 13 September.
They were released without charge on Monday, 11 September.