Published Tuesday, 30 June 2009
John McFall, chairman of the powerful Treasury Select Committee in the House of Commons, wrote to Mr Brown urging action.
Earlier this month the Prime Minister set up a working group aimed at saving the society - but it is not expected to report before September.
Some 9,500 members of the Belfast based society have seen their savings frozen and face losing millions after the collapse of the society, which is not covered by the government guarantees which protect savings in banks and building societies.
The fellow Scottish Labour MP and former Northern Ireland minister said his committee had been made particularly aware of the impact of the collapse on members when it visited Belfast in the spring and he had taken an interest in their plight ever since.
He wrote: "I understand the resolution is complicated, dependent on many external issues such as the speed and extent of recovery of the property market, the point at which assets are realised, and whether there will be any assistance from the Government."
However, he said: "I would ask that you urgently consider taking further action in this area, working with the Northern Ireland Executive and the Presbyterian Church to find a fair and expedient resolution of this issue."
Mr McFall said the Treasury Committee would continue to monitor developments closely and may return to the issue in the autumn.