Three male British teenagers suspected of planning to join Islamic State militants in Syria have been arrested by London police after being deported from Turkey, officials said yesterday.

The three, who have not been named, were detained on Friday in the Turkish city of Istanbul, Turkish sources told Reuters, after a tip-off from British authorities that two of them were travelling to Turkey via Spain.

London police said they had been made aware on Friday that two 17-year-old boys from the city had gone missing and were thought to be travelling to Syria.

Further inquiries by the police revealed they had travelled with a 19-year-old male, a police spokesman said.

They were then flown back to Britain late on Saturday, when they were arrested “on suspicion of preparation of terrorist acts”, the Metropolitan Police statement said.

Suspects flown back to Britain and arrested on suspicion of preparation of terrorist acts

Meanwhile the Turkish authorities confirmed that the young men had been deported.

They are being held at a London police station, the statement said.

Their arrest comes after three London schoolgirls entered Turkey last month and are thought to have joined Islamic State militants who are fighting in Syria.

Security services estimate that some 600 Britons have gone to Syria or Iraq to join militant groups, including the man known as “Jihadi John” who has appeared in several Islamic State videos showing the beheading of hostages.

Hundreds of other European muslims have also joined the fight by going to Syrian and joining the Islamic militants.

Their involvement with IS has raised fears about the possibility of attacks at home if they return trained and further radicalised.

Turkey meanwhile has faced criticism for not better controlling its southeastern borders. However, it has responded by accusing European countries of failing to prevent would-be jihadists from travelling in the first place.

On Thursday, the Turkish Foreign Minister insisted that the missing girls who had earlier travelled to Syria were helped to cross the border by a spy working for one of the countries in the US-led coalition against the militants.

Islamic State controls swathes of territory in Syria and Iraq where it has declared an Islamic caliphate.