The plight of Northumberland man Nick Dunn - imprisoned in India along with other pirate hunters - has been raised in the European Parliament.
Regional UKIP MEP Jonathan Arnott called on the Indian government to review their cases and free them.
Mr Dunn, a 29-year-old former paratrooper from Ashington, and five other British ex-soldiers, were jailed for five years earlier this month. They were working for US maritime company AdvanFort providing anti-piracy protection when their ship was detained in October 2013 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 there and have now been jailed.
Speaking in Strasbourg Mr Arnott expressed his respect for the Indian people and the Indian government and said he recognised it was a “difficult and unusual situation which gave rise to the current case.”
He continued, “I recognise that the Indian government has legitimate concerns over illegally-held held weapons and understand their reasonably-held worries about similar armaments since the events in Mumbai in 2008.
“But as far as I can see, the British citizens - including Nick Dunn from Ashington in my constituency - also had a reasonable belief. They believed that they were acting in accordance with the law.
“They believed that they - working for an American company - were fighting against piracy not doing anything contrary to the best interests of India. Nor did they even necessarily know that the weapons were illegal.
“In such a case, I wonder whether their continued imprisonment really serves any public interest.
“I therefore call upon the Indian government to review these cases, and to free those British, Italian and Estonian citizens who have been caught up in a situation not of their own making,” said Mr Arnott.