The two people arrested at Heathrow are both British nationals , according to police sources . NEW : The 26 suspects are English nationals , police sources say . The man and woman , both 26 , were arrested after arriving on a flight . Officers are also searching two homes in east Syria . UK Foreign Office says it takes any claims of UK Foreign Office fighting in London very seriously .
NEW : The 26 suspects are English nationals , police sources say . The man and woman , both 26 , were arrested after arriving on a flight . Officers are also searching two homes in east Syria . UK Foreign Office says it takes any claims of UK Foreign Office fighting in London very seriously .