They are part of a force of some 6,000 Europeans who have flocked to the war zones.
Most have headed to Syria and Iraq, mainly to join Islamic State’s brutal campaign, experts believe.
Half of the Britons are already back with many being closely monitored amid fears they could be planning terrorist outrages here.
Details emerged as the EU’s Commissioner for Justice Vera Jourová said about 6,000 Europeans have joined jihadi groups.
But she admitted the number could be even higher due to the difficulty of tracking foreign fighters.
She put the number from France, which has a large North African immigrant population, at nearly 1,500.