British teenage girls Shamima Begum, Amira Abase and Kadiza Sultana (L-R) walk through security at Gatwick airport before they boarded a flight to Turkey on February 17, 2015, in this combination picture made from handout still images taken from CCTV and released by the Metropolitan Police on February 22, 2015.

Ankara/Reuters: An alleged spy detained in Turkey for helping three British girls cross into Syria is a Syrian national working for a country in the U.S.-led coalition against Islamic State, the Turkish foreign minister said on Friday.

Mevlut Cavusoglu announced on Thursday that a spy who had assisted the three London school girls, now believed to be on territory controlled by Islamic State, had been caught, but did not give the suspect’s nationality.

Islamic State seized swathes of land last June, cementing their rule with a militant interpretation of Islamic law, and is drawing sympathisers from many countries to support their fight. The U.S.-led coalition is using mostly air power in an attempt to push the Sunni militant group back.

“The person who helped the three British girls into Syria is a Syrian national working for another country within the coalition. The situation is so complicated,” Cavusoglu told reporters in Ankara.

He did not say which country the spy was working for, although on Thursday he had said it was not the European Union or the United States. The coalition also includes countries such as Saudi Arabia, Qatar, Jordan, Bahrain, Australia and Canada.

The three girls, two aged 15 and one 16, flew to Istanbul from London on Feb. 17 and then onwards to Syria, where more than 200,000 have been killed in a civil war. Their families have appealed to them to return.

(Reporting by Tulay Karadeniz; Writing by Ece Toksabay; editing by Ralph Boulton)