A British film maker and his crew have returned home after spending 16 days in a Pakistani jail, accused of spying, in an incident which has led the Foreign Office to complain to the government of Pakistan "at the highest level".

Writer Tahir Shah from east London was arrested along with Swedish father and son Leon and David Flamholc while they were carrying out research for a Channel 5 documentary on looted Indian gold lost in Afghanistan during the 1700s.

The group had made a stop in Peshawar in the middle of last month on the way to Afghanistan to look up one of Mr Shah's relatives and were arrested after unwittingly filming outside a military compound.

"Suddenly we were intercepted by military police, who took us into their compound," said Leon Flamholc. "We were told we could not film and they took the camera away."

Within hours they had been blindfolded and thrown in cells, accused of spying, and were moved to an interrogation centre two days later.

"We asked to be able to contact our families or the British embassy, but we just weren't allowed anything," said Mr Flamholc, whose film company is based in London.

"Late at night they took away Tahir and interrogated him for a couple of hours blindfolded. When they took away the blindfold he could see he was in a torture room, with a lot of torture tools behind.

"We were scared because we know that there are some elements of the Pakistan army which are really mad Islamists. We just felt that they would bury us."

Despite the men spending two weeks in solitary confinement without charge, their captors failed to inform the British high commission that they were being held.

It was not until they convinced a guard to phone relatives in England that the men's ordeal drew to an end.

Mr Shah's sister, Saira, flew out to Pakistan and contacted the British high commission, leading to their release.

Mr Flamholc is considering taking legal action against the Pakistani authorities.