A U.N. panel warned last month that the number of foreign fighters in the conflict was growing — a development which it said could radicalize the rebellion against Assad’s rule. The Quilliam Foundation, a London-based think tank studying extremism, estimated that there were a total of 1,200-1,500 foreign fighters across Syria.
A British police statement said the man and woman were arrested on suspicion of the ‘‘commission, preparation or instigation of acts of terrorism.’’ The statement did not include the suspects’ names or any other identifying information.
Police said the possible link to the July abduction of the journalists was one of several lines of inquiry being pursuied.
Oerlemans, a prominent Dutch photographer who was shot twice during a failed attempt to escape from his captors, told The Associated Press Wednesday that the ages of the two suspects arrested at Heathrow was consistent with the ages of the people who held him hostage shortly after he entered Syria on July 19. But he said there were no women involved in the kidnapping.
‘‘But that doesn’t mean it’s not one of the guys in the camp,’’ he said of the man arrested at Heathrow.
The suspects were taken to a central London police station and remain in custody.
Paisley Dodds in London, Elizabeth A. Kennedy in Beirut, Lori Hinnant and Jamey Keaten in Paris and Michael C. Corder in Amsterdam contributed.