A majority of Scots believe the Labour Party has been guilty of selling honours and think Tony Blair should resign if aides are charged, according to polling commissioned by the SNP.

The survey of more than 1000 Scots showed 67% agreeing that Labour had sold peerages, while 64% took the view that the Prime Minister should resign immediately if any of his officials were detained.

Angus Robertson, the SNP's campaign director, said: "These figures are overwhelming - by a majority of over eight to one, people in Scotland believe that the Labour Party have been involved in selling peerages."

Mr Robertson said: "Even before the loans scandal, it was known that 80p in every £1 of individual donations to Labour came from people who were ennobled or honoured by Tony Blair.

"The problem for Labour in Scotland is that they are just a subsidiary of their London HQ, so depend on the same money for their Holyrood campaign and their campaign is being run by a Downing Street aide who has been questioned by the police over cash for honours, so it is clear that Labour in Scotland are mired in this crisis."

The YouGov poll conducted for the SNP among 1114 voters asked: "The police are currently investigating the alleged sale of peerages in the so-called loans for Lords affair. From what you know of the investigation do you believe the Labour Party has been involved in the sale of peerages?"

To that question 67% said "yes, Labour has been involved in the sale of peerages," while 8% answered "no, it has not". Those answering "don't know" totalled 26%.

The second question read: "If charges are brought against the Prime Minister's advisers or the Labour Party's fund-raiser as part of the police inquiry into the alleged sale of peerages, do you think Tony Blair should resign immediately?"

The findings were released as the SNP and Labour continued to trade insults on the economy yesterday, with Alex Salmond denying he planned to set impossible demands to Westminster if he wins power in Holyrood.

Mr Salmond said the issues set out in his party's plan for its first 100 days in power were both arguable and winnable.

Scottish Secretary Douglas Alexander accused the SNP leader of manufacturing "grudge and grievance".