Ten seafarers and 25 security guards from a US support ship have been sentenced to five years in prison after being held since 2013 in India in an arms row.

The Business Standard reported that the men from the 197-dwt Seaman Guard Ohio (built 1984) were also fined INR 3,000 ($45) each.

The crew consisted of eight Indians and two Ukrainians, while six Britons, 14 Estonians, four Indians and a Ukrainian were among the guards.

They were arrested when the vessel was sailing 15 miles off Tuticorin in October 2013, allegedly without valid documents for weapons and ammunition.

The vessel is operated by US security company AdvanFort.

All the men apart from the captain were cleared in 2014, but local police appealed and a trial was ordered.

The Mission to Seafarers said the men and their families are “deeply shocked and devastated” at the decision.

Ken Peters, the charity’s director of justice and public affairs, added: "I am horrified and filled with anguish at this decision which is deeply unfair and unjust.

“These men are seafarers but it seems the court did not accept the basic fact that the ship was and is an anti-piracy vessel.

“The men carried arms in accordance with international maritime law for the purpose of ensuring the merchant fleet was protected properly from the very real risk of pirate attacks and hijack. “

Defence lawyers are considering the possibility of an appeal.