London school girls
Shamima Begum, 15, Amira Abase, 15, and Kadiza Sultana, 16, left on a flight to Turkey on 17 February Met Police

Turkey said they have arrested a spy from an anti-Islamic State (Isis) coalition member state for allegedly helping three British schoolgirls join the jihadist group.

Shamima Begum, 15, Kadiza Sultana, 16, and 15-year-old Amira Abase, flew from London to Turkey on 17 February to then cross into Syria and are now believed to be living in IS's de facto capital Raqqa.

Turkey Foreign Minister Mevlut Cavusoglu said they were helped in their journey by a foreign agent. "This person was caught," he told broadcaster A Haber, Reuters reported. "It turned out to be someone who worked in the intelligence services of a country in the coalition."

The minister did not reveal the nationality of the agent but said they did not work for the US or any EU state. More than 60 countries, including a number of Arab states such as Saudi Arabia, Qatar and Jordan joined US-led operations against the extremist group in Iraq and Syria in September 2014. Cavusoglu said he has informed his British counterpart, Philip Hammond, of the development.

An FCO spokesperson 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 cooperation 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."

The Turkish government has been criticised by its Nato allies for allegedly not doing enough to prevent would-be-jihadists from crossing its long and porous border with Syria. In turn, Ankara claimed Western states have failed to provide it with enough intelligence on suspect travellers.

Thousands of Westerners have travelled to IS-held territories via Turkey, swelling the terror group ranks over the past two years.

Among them are Shamima, Kadiza and Amira, who boarded a flight from London's Gatwick Airport to Istanbul in February. CCTV images appeared to show the teenagers boarding a bus to Turkey's border city of Gaziantep, a notorious port of entrance for foreign fighters travelling to Syria.

Earlier in March, Scotland Yard's head of counter-terrorism, Mark Rowley, told lawmakers the girls are believed to have financed their escape by stealing jewellery from their families.