Britain's opposition Labour Party will give the Scottish parliament greater tax powers if Scots vote against independence from the United Kingdom, its leader Ed Miliband will say on Friday.
Polls show Scots are likely to vote "no" to independence in a referendum in six months' time, but the main parties in the Westminster parliament are trying to court undecided voters with promises of more devolution.
"A Labour government for the UK and a Scottish Labour government will be two governments working together on common challenges – not wrestling against each other," Miliband will tell a Scottish Labour Party conference on Friday, according to extracts of the speech supplied in advance.
Plans to extend devolution would include greater flexibility on setting income tax as well as giving the Scottish parliament more control over social security budgets, he will say.
Last week Conservative Prime Minister David Cameron also pledged to keep policymaking powers flowing north from London towards Scotland, saying that voting against independence did not mean choosing to keep the status quo.
A February survey by social research institute ScotCen found more Scots would prefer the Scottish parliament to be given greater powers to control their tax and spending than the riskier option of independence.
Scotland, which has had a devolved parliament since 1999, has lawmaking powers in areas such as education, housing and the environment. Under the current power-sharing arrangement, the British government sets policy on major areas like defence, benefits and energy.
Around 40% of Scots plan to vote for independence in this year's referendum, according to a poll on Thursday which showed a three-point rise in support for an end to the country's 307-year-old-union with England.