The campaign to secure full redress for Equitable Life policyholders has won support from the Scottish National Party as it takes its 15-year fight into another general election.

Equitable Members Action Group, with 10,000 members and a £250,000 annual budget, says there are 80,000 people in Scotland who have held Equitable policies and been cheated out of the compensation triggered when the Parliamentary Ombudsman found the government guilty of maladministration in 2008.

Despite a three-hour Commons debate last month, with several Scottish MPs among the 36 speakers, the coalition refused to revisit its 2010 decision to pay out only £1.5bn of a total losses of £4.3bn incurred by policyholders, due to the squeezed public finances.

Now Emag, formed in 2000 after the insurer collapsed, says it is canvassing fresh support from the potentially influential smaller parties at Westminster in preparation for yet another session of campaigning.

"We have been having dialogue with the SNP who are very supportive of our situation and are looking to do something about it in the next UK parliament," said spokesman Paul Weir. "Nicola Sturgeon has come out in favour of it. The SNP have said they want to take a cohesive approach and as far as they are concerned it is not done yet and it needs sorting out. We are working with all the minority parties at the moment to get leverage."

Mike Weir, the SNP candidate for Angus commented: "Equitable Life policy holders lost out because of the failure of UK government regulation.

"I believe this needs to be looked at again - with the aim of delivering a fair settlement."

Emag's secretary Paul Braithwaite wrote to all MPs last week as Parliament broke up, noting that the All-Party Group for Justice on the issue had 217 members led by three (Tory, Labour and LibDem) MPs, and thanking "every one of you who has bent the ear of your party hierarchies and marched through the division lobbies in our support, sometimes in defiance of the whips".

He went on: "We have had some great successes in the past few years - notably increasing compensation above the derisory level offered by the last government and securing recognition that pre-1992 with-profit annuitants had also suffered loss - but we have not achieved everything we would have hoped."

Some 8,000 pensioners mostly in their eighties who started policies before 1992, originally offered nothing, were last year handed £5000 apiece as a result of Emag's campaign.

But almost 950,000 people are still receiving compensation for just 22.4per cent of their acknowledged losses. "We continue to see correspondence from the Treasury to MPs that is then passed on to our members containing inaccurate statements and significant omissions," Mr Braithwaite wrote.

Mr Weir said the Treasury still appeared to be "in denial" that government had been at fault, as the Labour administration had maintained for eight years. "The common thread is Treasury civil servants who are still working to a very old script written by Gordon Brown."

He went on: "We have tried to make it easy for them - if the lump of money looks too big, why not stage it over the next parliament which is something less than £600m a year."

On whether Emag would continue, Mr Weir said: "Quite simply after 15 years I am still £50,000 down. I am not just going to write it off, that would make a huge difference to my retirement, and it's my money and I want it - everybody feels like that."

The SNP plans to oppose any further increases in the state pension age in the next parliament, Ms Sturgeon said earlier this week. She said Scotland with its comparatively low life expectancy rate would be disproportionately impacted and it would be "completely unacceptable for people in Scotland who have paid in to a state pension all of their lives to lose out".