The Ulster Unionists were in the red by almost £0.5 million sterling last year, it was revealed today.
According to figures released by the Electoral Commission, Sir Reg Empey's party had debts of over £450,000 last December at the end of a bitterly disappointing electoral year.
In a statement accompanying its accounts reviewing what it described as a difficult year, the UUP acknowledged the existence of two party bank accounts which had not figured in the 2004 end of year financial statement.
The previously undeclared bank accounts were referred to the police last month by the Electoral Commission for investigation.
The Rev Ian Paisley's Democratic Unionist Party, which had their best ever set of Westminster and Local Government Election results last year, also recorded debts last year of over £52,000.
Its statement revealed the party had 2,912 members by the end of the year, with three new branches formed in Erne North in Co Fermanagh, Killultagh and Ballyclare in Co Antrim.
Three branches ceased to exist in Donaghadee and Moira in Co Down and Ballinamallard in Co Fermanagh but were swallowed by other branches.
Mark Durkan's nationalist SDLP, which was beset with debts years ago, recorded a surplus of over £58,000.
The party recorded a slight fall in its income from party members from over £76,500 in 2004 to over £68,000 last year.
It also saw donations and fundraising fall from over £565,000 to over £334,000. However conference income increased, as did the value of a policy grant from the Electoral Commission.
The SDLP vowed to make "strenuous efforts to increase its membership during 2006 as well as taking steps to improve our fundraising activities."
After recording a £200,000 deficit in 2004, Sinn Fein returned a surplus of over £1,300.
The party said this was due to an increased contribution from its elected representatives which rose from over £348,000 in 2004 to more than £482,000 last year.
However political donations to Gerry Adams' party fell from almost £181,000 in 2004 to over £137,000 last year.
In a statement accompanying the accounts, Sinn Fein said it expected 2005 to be a tough year financially following the decision by the British Government to stop its Assembly Party Allowance and its Westminster allowances.
"In November our Assembly party allowance and our Westminster allowances were restored and we finally got the equivalent of short money," the party noted.
"However we still have not got the policy development grants which the other parties have long enjoyed. We will continue to rely on the generosity of our elected representatives and our donors especially, as always, Friends of Sinn Fein."
The cross community Alliance Party recorded a deficit of over £42,000 but insisted it remained in a reasonable financial shape.