The First Minister yesterday appealed to the Scottish Trades Union Congress to help persuade people to keep an open mind about independence during the SNP's "national conversation".

He praised the STUC's unimpeachable historical credentials on home rule, in contrast to those who spent their entire political lives campaigning for self-determination for every country on the planet with the sole exception of Scotland.

Mr Salmond's address to the STUC 111th annual congress, being held in Inverness, paid testimony to the body's deep commitment to Scotland which stretched back long before the SNP was even formed.

"The STUC pursued a policy of self-government for Scotland when it wasn't fashionable. Looking back through the annals of the history of this congress, I found that in 1918 the delegates were pursuing separate Scottish representation at Treaty of Versailles after the First World War because of the particular aspects that they wanted to give to the peace negotiations.

"Through periods when no mainstream political party was at all interested in the cause of Scottish self-government, the STUC was the organisation which kept the flame burning year after year at the STUC congress.

"Now everybody and their auntie is in favour of more powers for the Scottish Parliament and therefore it is entirely fitting and appropriate that this congress welcomes discussions, arguments and debates which don't foreclose any option."

Mr Salmond, the first SNP leader to address the STUC, said he was delighted that it had welcomed his party's national conversation about the future of Scottish government and saw a particular role for the body.

He said: "I am sure that the STUC will prevail on others not to close their minds to independence as a political objective."

He said the history of the STUC had shown that it believed these were matters that the Scottish people were entitled to determine for themselves, founded on the principles of self-determination.

"I have met a range of people in my political career who had a dualistic attitude to the question of self-determination. There was the self-determination they supported for every other community of nations around the world, except in the case of Scotland when they found the concept of self-determination difficult."

The STUC had never adopted this dualistic approach. It had always sought the same rights and entitlements for Scotland it would wish for any other country, he said.

Meanwhile, Wendy Alexander, the Holyrood Labour leader, also appealed directly to the shared history of the trade union movement and the Labour Party which together had helped change the course of history.

She promised that the STUC's voice would be listened to in the commission Labour had help set up to examine Scotland's constitutional future.

She attacked the SNP government for being "propped up" by the Tories. She added: "This weekend, Alex Salmond told his own conference that if he wins 20 seats at Westminster, London would be forced to dance to a Scottish jig. It's break-dancing Mr Salmond is more interested in, breaking up the UK in jig-time."

Ms Alexander told the conference: "The fact that the SNP are so keen to talk up the Tories should ring alarm bells across Scotland.

"Have the SNP learned nothing in the 30 years since 1979 - when they put the Tories into power ushering in Thatcherism - and now it seems they are wanting to repeat the same thing all over again?"

Already there was much to be concerned about, she said. "In Alex Salmond's Scotland some people are indeed more equal than others. The Trump Organisation, Macdonald Hotels in Aviemore, ScottishPower - all big businesses with a special pass to the corridors of SNP power."

The Scottish Government disregarded "the most basic levels" of transparency scrutiny and accountability in the letting of the contract for rail services, and ignored a request by unions to discuss a £150m contract for 120 railway carriages, she said.

"We don't need a special access government in Scotland that favours its friends."