Belfast City Council has called on the Prime Minister to guarantee savings worth up to £50,000 at the crisis-hit Presbyterian Mutual Society.
The plea for help from Gordon Brown came as thousands of people face losing their savings after the society was placed into administration in November.
Last week, 23 former Presbyterian moderators wrote to the British and Irish governments, asking them to intervene.
Ulster Unionist leader Sir Reg Empey proposed last night’s council motion, passed unanimously, calling for the cash promise.
He said: “Members felt that there was a grave injustice being done to small savers in Northern Ireland who were being abandoned by the Treasury, while others, including those with funds offshore in Icelandic banks, were having their savings guaranteed.
“There was also anger that billions of pounds of taxpayers’ money was going to bail out those who squandered money on dodgy investments at the same time as Government was refusing to help out its own citizens who invested in sound properties.”
He added: “I believe the support we have received here tonight indicates the strength of feeling accross Northern Ireland about this issue.
“We want these society savers helped and not left to swing in the wind, while the reckless lenders are bailed out.”
Last week the moderators said part of the problem was linked to the Government’s failure to extend its savings guarantee to the society. They added that Downing Street was under a moral obligation to intervene.
DUP Assembly member Arlene Foster hopes to meet Mr Brown within a week about the plight of savers.