A foreign spy has been detained on suspicion of helping three British schoolgirls travel to Syria to join Islamic State (IS), the Foreign and Commonwealth Office (FCO) have confirmed.

The nationality of the person arrested remains unclear, but the FCO and Met Police have said they are working closely with the Turkish authorities.

An FCO spokesman said: "We are aware that an arrest has been made by the Turkish National Police and that the Metropolitan Police have informed the families of the three girls.

"There has been close co-operation between ourselves and the Turkish authorities, and the Foreign Secretary is in regular contact with his Turkish counterpart. As soon as the UK received this information it was acted upon appropriately."

Turkish foreign minister Mehmet Cavusoglu has told reporters that the detained suspect works for the intelligence agency of a country that is part of the US-led coalition against IS.

Mr Cavusoglu did not identify the country but said it was not the United States or a member of the European Union.

Mr Cavusoglu, who was interviewed on Turkish channel A Haber TV, said he had shared the information with his British counterpart, Foreign Secretary Philip Hammond.

Shamima Begum, 15, Kadiza Sultana, 16, and 15-year-old Amira Abase flew from Gatwick to Istanbul on February 17 and are feared to have continued to Syria to become so-called ''jihadi brides'' with IS militants.

In the interview, Mr Cavusoglu said: "Do you know who the person who helped the girls turned out to be? Someone who works for the intelligence service of a country that is part of the coalition. It is not an EU member, it is not the United States either."

The three girls paid more than £1,000 in cash to a travel agent for their flights to Turkey and police officers believe they stole jewellery from relatives to fund the trip.

Turkish ambassador Abdurrahman Bilgic said earlier this week that British delays in handing over information about the girls had slowed down action in his country.

Despite the girls boarding a flight on Tuesday February 17, Turkish embassy officials were only informed at 7.55pm the next day by email, which was picked up the following day, he said.

Metropolitan Police Commissioner Sir Bernard Hogan-Howe has apologised for failing to communicate more directly with the girls' families - but insisted there was nothing more the force could have done to stop them from leaving.

The three teenagers were among seven schoolgirls who were handed letters by the police about another 15-year-old who ran away to Syria in December.

Families of the girls told MPs earlier this week there was no indications the girls had been radicalised, with Shamima's sister Sahima Begum pointing out that her sister ''was into normal teenage things'' and used to watch Keeping Up With The Kardashians.