Three British teenagers arrested in Turkey after allegedly plotting to join Isis in Syria are now in custody at a London police station.

On Friday, officers from the Metropolitan Police's Counter Terrorism Command were made aware that two 17-year-old boys from northwest London had gone missing and were believed to be travelling to Syria.

Inquiries revealed that they had traveled with a third male, aged 19.

Officers alerted the Turkish authorities who were able to intercept all three males, preventing travel to Syria.

It has since emerged the suspects arrived back in the U.K. on Saturday, at approximately 11:10 p.m. and were arrested on suspicion of preparation of terrorist acts contrary to Section 5 of the Terrorism Act 2006.

All three have been taken to a central London police station, where they remain in custody.

Inquiries continue.