Annabel Goldie called on Alex Salmond to reveal where the cuts will be made
The SNP must "come clean" and detail where cuts in public spending will be made, the Scottish Tories said.
The demand came after claims senior civil servants were making plans to cut public sector spending by 5%.
Scotland on Sunday also reported that tax increases were being planned, according to leaked minutes of a meeting of the SNP's top officials.
A spokesman for Finance Secretary John Swinney said the meeting in question was not part of the budget process.
Scottish Conservative leader Annabel Goldie said: "This is now clear evidence that Labour's handling of the economy has severely damaged the public finances.
"However rather than trying to hide behind a doomed separation bill, Alex Salmond needs to come clean and say where he plans to make cuts.
"I have been challenging the First Minister on how he will respond to Labour's £500 million budget squeeze.
"Where he is going to take the tough decisions, what is he going to cut? I have yet to get an answer from him."
Ms Goldie said economists from Glasgow University believed the recession meant there would be cuts of £2.5bn in Scotland's budget over the next four years.
She added: "If Alex Salmond's SNP government chooses to ignore this, or make political capital out of it rather than dealing with the situation, then Scotland will be in real trouble."
Labour said a 5% cut in spending from every single Scottish Government department, with no exceptions, would amount to cuts of about £2bn a year.
But the SNP said Labour and the Tories had demonstrated "unbelievable hypocrisy".
SNP Finance Committee member Joe Fitzpatrick said: "It is the UK Labour Government's spending cuts that are responsible for slashing Scotland's budget by £500m a year - and the Tories also plan to impose swingeing cuts in Scotland's budget if they get elected.
"Peter Mandelson has admitted that UK Governments will be cutting budgets for the next 10 years and only yesterday Alistair Darling was talking about cutting spending and increasing taxes."
He added: "Labour and the Tories should both agree with the SNP and dump the multi-billion Trident nuclear missile programme, instead of cutting jobs and services."