UPDATE 1-UK anti-terrorist police arrest man after Turkey deports suspects

British police arrested a 26-year-old man at Heathrow Airport who had arrived from Turkey on Thursday, on suspicion of terrorism offenses related to Syria.

"He was arrested on suspicion of preparation of terrorist acts," London's Metropolitan Police said in a statement. "The arrest is Syria-related." Turkish authorities have begun to send Islamic State detainees back to their home countries with the country's interior ministry earlier saying it was deporting one British and seven German fighters on Thursday.

Ankara says it has hundreds of more jihadists in detention and has accused European countries of being loath to take back citizens who traveled to join Islamist militants fighting in Middle East wars, mainly in Syria and Iraq. Some 10,000 Islamic State detainees and tens of thousands of family members remain in camps and prisons in northeastern Syria guarded by the Syrian Kurdish allies of the United States.

Washington is also pushing European countries to take their citizens back.