Gordon Brown has outlined a 14-point plan for new powers for the Scottish Parliament following the referendum vote to stay in the union.
And he wants 100,000 Scots to sign a petition demanding that Westminster keeps its vow to deliver more devolution.
His comments come just two weeks before he leads a debate in the House of Commons on the issue - and as a warning after the Prime Minister appeared to link the new powers to restricting Scottish MPs from voting on English matters.
Mr Brown’s extra powers blueprint includes more control over investment, job creation, welfare, transport, elections and taxation.
He wants the transfer of up to £4 billion of VAT revenues to the Scottish Parliament alongside devolving the majority - but not all - of income tax, branding that move as ‘‘a Tory trap.’’
He explained: ‘‘This trap would end income tax as a shared tax and threaten to reduce the rights of Scottish representatives at Westminster on budget tax decisions.’’
Mr Brown joined David Cameron, Prime Minister, Nick Clegg, Deputy Prime Minister and Ed Milliband, Labour leader, in signing what has become known as ‘‘the vow’’ to commit them to a clear timetable of delivering new powers to Scotland.
This week he wrote to his constituency party updating plans for the Scottish Parliament post-referendum.
Mr Brown said: “The vow made by three party leaders was a self-standing set of promises to the people of Scotland.
“Yet immediately after the referendum result, a new proposal that was never raised in the pre referendum discussions and yet being material to the referendum should have been raised before the vote was introduced - to lower the status of Scottish MPs in the UK when voting on matters including tax.
“I agree with the chairman of the previous Conservative review, Kenneth Clarke, that care has to be taken to get the precise changes right, and at this point we need to understand that whatever the disagreements now over the status of Scottish MPs, the pre-referendum vow signed by each of the pro-devolution parties’ leaders contained no ifs, no buts and had no conditional clauses and no strings attached.
‘‘It was not presented as part of wider proposals yet to be unveiled, but as stand-alone and self-contained.”
Mr Brown will lead the debate at Westminster on October 16.