FORMER prime minister Gordon Brown has offered to spearhead moves for greater powers for Scotland in the event of a vote against independence.

As Labour seeks to win over disaffected former party supporters, Labour's ex-leader and last prime minister used a speech at Westminster to announce he planned to lead a debate in the House of Commons on the issue as soon as possible after September 18.

In an apparent break with some in the pro-Union side, he also rejected suggestions from some Conservatives that extra powers for Holyrood especially on tax should see MPs barred from voting on those matters at Westminster.

The move would place the former prime minister front and centre of the push towards extra powers.

The pro-Union parties want to remove any doubt a No vote will not simply mean the continuation of the status quo.

The SNP has accused the pro-Union parties of trying to con voters with claims of extra powers with no specifics attached.

Labour, Liberal Democrat and Conservative plans for extra powers differ and their offers to the Scottish electorate are expected to be contained in manifestos ahead of next year's general election.

The issue has proved extremely controversial among some Conservative MPs.

One, former Tory leadership contender, John Redwood, has even suggested Scots MPs should be barred from voting on taxes at Westminster that do not directly affect Scots.

Mr Brown's offer suggests he will be at the forefront not just for the referendum campaign but in the push to deliver extra powers after the vote.

He is also due to appear on a platform with Ed Miliband for the first time since the 2010 general election next week as the Labour leader and former leader campaign against independence. Mr Brown urged voters not to "abandon" the huge value to Scotland of pooling resources with the rest of the UK in areas such as pensions and healthcare.

He accused the SNP of failing to give the issue of social justice the same priority as Labour saying: "We wake in the morning thinking about how we can help people out of poverty and get people into jobs ... how we can build a better health service, better education services for our children," he said.

"They wake up in the morning with one ambition: to break every single political link with the United Kingdom."

Mr Brown said the aim of extra powers in the event of a No vote should be the "maximum local decision-making powers that is possible" while maintaining the Union.

He added: "This is not like 1979 when the then-Conservative government promised change and then denied us it. This is like 1997 when the Labour government came in and, within a year, had delivered its promise of a Scottish parliament.

"When we are talking about the future of the constitution, London must and will change, Westminster must and will change, and, of course, the United Kingdom must and will change."

Asked about claims from Tory MPs that Scots should have restricted voting rights in the House of Commons, he said: "I think the Conservatives will have to accept these proposals ... the strong weight of opinion for them.

"We stand ready to talk to other parties about how we could reach a consensus on these proposals for the future."

He later said: "We have got to recognise the asymmetric nature of the British constitution, find a way of accommodating the ambitions of all the different nations -and indeed the regions."

And he dismissed calls - again by some Tory MPs - for an English Assembly.

"The English do not want a parliament of their own. If they wanted it, that would be an issue, but there is no evidence that there is a desire for an English parliament," he said.

He also dismissed SNP plans for a corporation tax cut as "the Scots Nats backing the fat cats and obviously cheered on by the cybernats".