ANKARA (Reuters) - Turkey said on Thursday it would deport an American suspected Islamic State fighter to the United States after he was refused entry to Greece, and sent eight people with links to the group to Germany and Britain.

NATO allies of Turkey in Europe have been worried that Turkey’s offensive last month into a Syrian border area could lead to Islamic State suspects and their families escaping from prisons and camps run by Kurdish forces. Ankara has dismissed the concerns.

Turkish authorities said on Monday they had begun to send Islamic State (IS) detainees back to their home countries, deporting a German and an American. A further 23 European nationals would be sent home in the coming days.

Greek police said on Monday Turkish police had come to the Kastanies border post and requested that a U.S. citizen of Arab descent accompanying them be let into Greece, as he had been arrested for exceeding his maximum permitted stay in Turkey.

The man was refused entry and returned to Turkey, Greek police said. However, Turkish state media said the man had remained in a buffer zone between Turkey and Greece.

On Thursday, the Interior Ministry said the United States had agreed to take back the man, who had requested deportation to Greece prior to being denied entry, and that Turkish authorities had begun the necessary proceedings.

Washington is working closely with Turkey and Greece to track the case, said Nathan Sales, the U.S. State Department’s counterterrorism adviser, who cautioned against asking nations to take on another country’s fighters.

A man, a U.S. citizen of Arab descent and Islamic State suspect who was deported by Turkey, stands on the no-man's land between Turkey and Greece, as he is pictured from the Pazarkule border crossing near Edirne, Turkey, November 11, 2019. Picture taken November 11, 2019. Ali Can Zeray/Demiroren News Agency (DHA) via REUTERS

“Our view is that it is not a feasible option, it is not a viable option, to ask other countries in the region to import another country’s foreign fighters and pursue prosecution and incarceration there,” Sales told reporters.

Separately, seven prisoners deported from Turkey landed in Berlin, a Reuters witness said. The group, which included two men, four women and a child, were driven away in a vehicle.

Germany’s foreign ministry had said on Monday that Ankara had informed Berlin of 10 people it aimed to deport - three men, five women and two children. The ministry has said it does not know whether any were Islamic State fighters but it confirmed their German citizenship.

German authorities were not expected to arrest them.

Police in London said they had arrested a 26-year old man at Heathrow Airport on Thursday on suspicion of terrorism offences related to Syria. He had arrived from Turkey but it was not immediately clear if he was the British fighter that Turkey said it would deport.

Turkey says it has captured 287 fighters in northeast Syria since launching a cross-border incursion on Oct. 9 targeting the Kurdish YPG militia. It says it has hundreds 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.

Ankara views the YPG, the main component of the U.S.-backed Syrian Democratic Forces (SDF) that helped the United States defeat Islamic State, as a terrorist group that backs a Kurdish insurgency on Turkish soil.

Thousands of militants were jailed in YPG-controlled territory after the collapse of the IS “caliphate” in 2017, and tens of thousands of their relatives are kept in camps there.

President Tayyip Erdogan held talks with U.S. President Donald Trump in Washington on Wednesday and Erdogan said he told Trump that Turkey expected the United States to halt its support for the YPG.

Turkey has said it will send some detained militants to Ireland, Denmark and France in the coming days.