Scotland's trade unions demanded answers over welfare, currency and industry from both sides of the independence debate yesterday as their members decide how to vote in September's referendum.

The Yes Scotland and Better Together campaigns have worked hard to win support from Scotland's 27 trade unions and their 630,000 members.

But the Scottish TUC has posed tough questions for both groups in its second report on the future of Scotland, launched in Edinburgh yesterday.

The report asks the Scottish government to explain how a Nordic-style welfare system could be paid for without raising tax on businesses and the middle classes.

Deputy general secretary Dave Moxham told the Star: "The Scottish government is projecting a vision of social justice that will be very attractive to some of our members.

"The problem is that there are a number of serious questions about currency and commitments on tax and redistribution that don't chime with the vision they are presenting."

The Labour, Tory and Lib Dem parties are challenged to set out what extra powers Scotland would gain after a No vote.

Mr Moxham added: "The failure of the three pro-devolution parties to come up with a new vision of what a devolved Scotland might look like after a No vote, particularly in terms of social justice, is weighing down on their campaign."

The STUC report includes evidence submitted by the Red Paper Collective, which aims to put class at the front of the independence campaign.

A spokesman for the collective said: "The STUC is right to be sceptical of the SNP's claim that the low tax business friendly Scotland it plans will build a fairer or more equal society.

"The STUC is also right to challenge the parties supporting a No vote to outline their plans for a future."

The latest poll by Survation put Yes at 37 per cent and No at 47 per cent.