British police said on Saturday they had arrested six people at the southern English port of Dover on suspicion of terrorism offences related to the ongoing conflict in Syria.
The five men and one woman, all aged in their 20s, were detained on Friday morning in the departure zone of the port, West Midlands police said.
The group were now in custody in central England and searches were underway in Birmingham where the men lived. The suspects did not pose any immediate risk to the public, police added.
British security services estimate some 600 Britons have gone to Syria or Iraq to join militant groups, including the man known as "Jihadi John" who has appeared in several Islamic State beheading videos. About half are thought to have returned.
On Wednesday, Turkish security forces detained nine British nationals who were apparently attempting to enter Syria. The group, five adults and four children from Rochdale in northern England, included the 21-year-old student son of a local councillor.