Relatives of a group of former British soldiers, including two from the North West, who have been jailed in India delivered a 100,000-strong petition to Downing Street today.
Supporters, including families of the six men, are urging Prime Minister David Cameron to intervene.
They have also launched a campaign to raise money for a "fighting fund" to help their loved ones in prison.
Ray Tindall from Chester; Paul Towers, originally from Bootle in Merseyside, Billy Irving, from Connel, Scotland; Nick Dunn, from Ashington, Northumberland; John Armstrong from Wigton, Cumbria, and Nicholas Simpson, from Catterick, North Yorkshire, were arrested on October 12 and have been in prison in India since October 24.
The men were working for US private maritime company AdvanFort providing anti-piracy protection when their ship was detained.
According to the men, Indian authorities claim the vessel entered Indian waters illegally with weapons on board, despite AdvanFort apparently insisting the ship had the correct papers.
A petition, set up on online platform Change.org, calls on the Government to step in and help the men.
Maritime welfare charity The Mission To Seafarers has been providing prison-visiting services to Chennai prison where the men are being held and working to support families in the UK.
According to the charity a bail hearing for the men will be held on Thursday or Friday.
The organisation is helping to manage a fundraising campaign in support of the men.