Two British journalists who were detained in Libya have revealed they were held because their captors confused a passage of Welsh written on their medical supplies for Hebrew, leading to suspicions they were spying for Israel.

Gareth Montgomery-Johnson, from Carmarthen, and Nicholas Davies-Jones, from Berkshire, flew back to the UK on Monday night after being held by a militia group for three weeks.

Mr Montgomery-Johnson said yesterday that things had been going well until they were taken into detention in Tripoli on 22 February by the Misrata Brigade. After two hours they realised they were in serious difficulty, but it was five days later when the militia began inspecting their equipment that a mistranslation posed even greater problems.

"My father, who's a nurse, had given me some bandages in case we got into trouble," he told the BBC. "Some had Welsh written on and they thought this was Hebrew and we were Israeli spies." It was an ironic mistake given that they were working for Press TV, the state broadcaster for Israel's sworn enemy, Iran.

The pair had been held in what Mr Montgomery-Johnson described as "a small room, 3m by 3m" in a military barracks in the middle of Tripoli. "The conditions were not good at all," he added. It was not until 14 March that the hostages were handed over to the Libyan Interior Ministry, which granted their release when it realised they were innocent.

Speaking of their return to the UK, Mr Montgomery-Johnson said they felt "overwhelmed". "We're pleased to be back with our own families," he said, "because they've been through a similar ordeal."

Despite Welsh being a Celtic language with Indo-European heritage, while Hebrew has ancient Afro-Asiatic origins, the confusion between the two may not be as far-fetched as it first appears.