Transport workers union the ITF is putting its cash behind the appeal of the Seaman Guard Ohio crew against their jailing in India on weapons charges.

Ten seafarers and 25 security guards from the US-operated support ship were sentenced to five years in prison earlier this month after being held since 2013.

They were arrested when the 197-dwt vessel (built 1984) was sailing 15 miles off Tuticorin in October 2013, allegedly without valid documents for weapons and ammunition.

ITF