An MP said it was a "miscarriage of justice" that six British ex-soldiers working on an anti-piracy mission have been jailed in India on weapons charges.
Ian Lavery, Labour MP for Wansbeck, said he will continue to campaign for constituent Nick Dunn and the other five men who have gone through what he called "years of hell".
They were security guards on a US-owned ship when they were arrested in October 2013 on illegal weapons charges.
There were hopes that the latest legal hearings in India would see them free to return to the UK.
But instead they have been jailed for five years.
Mr Lavery said: "This verdict will have come as a hammer blow to Nick Dunn and the other men detained in India coming only a matter of months after a court had quashed all of the charges.
"The men and their families will be distraught at this news with all noises coming out of the courts in the last few days and weeks pointing towards them returning home in the near future after years of hell.
"Sadly this bizarre judgment, charging the former British servicemen with the maximum penalty for handling arms, means the nightmare continues.
"My thoughts this morning are with the men, their families and friends whose worst fears will this morning have been realised by the judgment.
"I will continue to work with Nick's family to fight for his release and return to the UK and am seeking urgent discussions on the way forward and seeking an early resolution to this miscarriage of justice."
As well as Mr Dunn, from Ashington, Northumberland, the detained men are Ray Tindall from Chester; Paul Towers, from Yorkshire; John Armstrong, from Wigton, Cumbria; Billy Irving, from Connel, Argyll, and Nicholas Simpson, from Catterick, North Yorkshire.
They were working for US maritime company AdvanFort providing anti-piracy protection when their ship - MV Seaman Guard Ohio, which had a crew of 35 - was detained and weapons were found.
In the following months the charges were dropped, but the Indian authorities appealed against the decision and the men were detained in India.
The authorities have now won their case.