A man suspected of fighting in Syria has been arrested on his return to the UK.

The 32-year-old suspect was detained at Luton Airport on Thursday evening.

Police said he was arrested on suspicion of preparing acts of terrorism – a law used to prosecute foreign fighters as well as terror plotters.

A spokesperson for the Metropolitan Police said the man was stopped at around 8.30pm on Thursday after arriving on an inbound flight.

“He was arrested on suspicion of preparation of terrorist acts and taken to a police station in the Bedfordshire area, where he remains in custody,” a statement added.

“The investigation is being conducted by detectives from the Met’s Counter Terrorism Command.

“The arrest is Syria-related and not related to any offences at the airport. Enquiries continue.”

Police have arrested suspects for joining, or attempting to join, Isis and al-Qaeda affiliates in Syria, as well as Kurdish groups supported by the UK to battle Islamists on the ground.

Officials would not immediately say which group the suspect, who was being interviewed, is accused of joining.

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The Foreign Office has advised against all travel to Syria since the start of the country’s ongoing civil war, and police have said anyone going to fight can be arrested regardless of their cause.

Of an estimated 900 people of “national security concern” who travelled from the UK to Syria, around 20 per cent have been killed and 40 per cent have returned.

Officials say that the majority of returnees came back in the earlier stages of the conflict, and a “significant proportion” are assessed as no longer being a threat.

Authorities have become increasingly adept at preventing Isis supporters from travelling abroad, but the head of national counterterror policing recently warned they may then plan terror attacks in Britain instead.

Metropolitan Police assistant commissioner Neil Basu said that before last year’s attacks security services believed that fighters returning from abroad presented the biggest threat.

“It wasn’t – the threat was already here – and there are still plenty of aspirant or frustrated travellers who now have nowhere to go,” he told a conference.

Two of the London Bridge attackers had wanted to travel to Syria before they started plotting the atrocity, and several others who were prevented from carrying out attacks mounted terror plots after their original desire to join Isis abroad was thwarted.

Syria bombings: US, UK and French military air strikes wreckage Show all 13 1 /13 Syria bombings: US, UK and French military air strikes wreckage Syria bombings: US, UK and French military air strikes wreckage The wreckage of the Scientific Studies and Research Centre in the Barzeh district, north of Damascus, which was targeted by the US, UK and France air strikes. AFP/Getty Syria bombings: US, UK and French military air strikes wreckage A Syrian soldier films the damage of the Syrian Scientific Research Center surrounded by papers and rubble. AP Syria bombings: US, UK and French military air strikes wreckage Firefighrers extinguish smoke that rises from the damage. The Pentagon says none of the missiles filed by the U.S. and its allies was deflected by Syrian air defenses, rebutting claims by the Russian and Syrian governments. AP Syria bombings: US, UK and French military air strikes wreckage The wreckage of part of the Scientific Studies and Research Centre compound . AFP/Getty Syria bombings: US, UK and French military air strikes wreckage Part of a building collapsing, surrounded by the wreckage. AFP/Getty Syria bombings: US, UK and French military air strikes wreckage Further damaged to the Scientific Studies and Research Centre compound. AFP/Getty Syria bombings: US, UK and French military air strikes wreckage Lt. Gen. Kenneth McKenzie, the director of the Joint Staff at the Pentagon, also says there also is no indication that Russian air defense systems were employed early Saturday in Syria. AP Syria bombings: US, UK and French military air strikes wreckage A Syrian soldier sprays water on the wreckage. AFP/Getty Syria bombings: US, UK and French military air strikes wreckage Syrian state news agency SANA reported several missiles hit a research centre in Barzeh, north of Damascus, "destroying a building that included scientific labs and a training centre". AFP/Getty Syria bombings: US, UK and French military air strikes wreckage A Syrian soldier films the damage. AP Syria bombings: US, UK and French military air strikes wreckage Damage to the Scientific Research Center building that was hit by the strikes. EPA Syria bombings: US, UK and French military air strikes wreckage The Scientific Studies and Research Centre was one of the targeted buildings by the US, UK and France. AFP/Getty Syria bombings: US, UK and French military air strikes wreckage Further damage to the centre. EPA

The UK has suffered five terror attacks since March 2017, which killed 36 victims last year, and security services have foiled 13 Islamist and four extreme right-wing plots in the same period.

In the year to September, 40 per cent of terror suspects arrested were white, 33 per cent were Asian, 12 per cent were black and 14 per cent were recorded as other.