Some reports say they were arrested in Helmand province, but an Afghan source told the BBC they were arrested at a hotel in Herat in a joint operation between local forces and UK troops.The source added that the pair had dual citizenship but were not Afghans.

 

Nato forces in Afghanistan usually hold suspects for up to 96 hours before they are freed or sent to local authorities. However, this can be extended in certain cases.

 

BBC security correspondent Gordon Corera said: "The two Britons picked up in Herat in recent days are believed to have gone to Afghanistan from the UK. "They may have been under suspicion here and it’s thought they had gone out to Afghanistan probably to make contacts." He said they may have met people, potentially militants, with a view towards training and then carrying out some kind of attack back in the UK – but that is not certain.

 

And the BBC’s Bilal Sarwary, in Kabul, quoted an Afghan intelligence official in Herat as saying: "Our agents played a key role in the arrests. Both were staying at a local hotel in the city."

 

An MoD spokesman said: "We can confirm that British forces have detained two individuals in Afghanistan who claim to be British nationals. We are not prepared to comment further at this stage."

 

The Foreign Office said embassy staff were "providing assistance".