The SNP has "absolutely no mandate" to hold a second referendum on independence, Labour MP Ian Murray has told the party's Scottish conference.

Mr Murray said Labour would oppose any moves to hold a second vote as he opened a debate on proposals for a more federal UK.

The party's only Scottish MP issued the warning amid growing speculation Nicola Sturgeon will announce a rerun of the 2014 independence ballot in the coming weeks.

"I want to make it absolutely clear to both Nicola Sturgeon, and indeed to Ruth Davidson, the SNP has absolutely no mandate for another Scottish independence referendum," Mr Murray said.

"If they try to push one through, Scottish Labour will oppose it in the Scottish Parliament all the way."

The First Minister has said another referendum is "highly likely" following the Brexit vote last year.

Mr Murray said the Conservatives were to blame for the prospect of another vote dominating the political agenda, branding the party as the "the SNP enablers".

"It is they who are really responsible for this current mess - Nicola Sturgeon's mibbes aye, mibbes naw referendum," he said.

"Thanks to them, the constitution has barely been off the agenda since the early hours of September 19."

Mr Murray asked party members to endorse Scottish leader Kezia Dugdale's vision for a new "Act of Union" for the UK in response to both Brexit and calls for a second independence referendum.

A motion put before the conference in Perth calls on the UK party to convene a "People's Constitutional Convention", made up of citizens from across the UK, which would then report back before the 2020 general election.

That convention is part of Ms Dugdale's proposals for a more federal UK, which would also see increased powers for Holyrood, Cardiff Bay, Stormont and the English regions.

Mr Murray said: "The vision before you today is one of hope and optimism.

"It will mean that every part of the UK and every part of Scotland is contributing to our success.

"It will reforge our democracy and our society, and safeguard it for the future.

"This is an historic moment for our party. Labour, the party of devolution - now ready to seize the mantle as the party of federalism.

"The party that stands up for what the majority of people in Scotland want - firmly, unquestionably opposed to independence, but also opposed to the status quo. The party that believes together we're stronger.

"Today our country is deeply divided, not just by constitutional politics but by economic inequality.

"To restore faith in our politics, to build a more united society and create an economy that works for working people, we believe that we need to create a more federal UK."

There was broad support at the conference for Ms Dugdale's vision of a more federal UK.

Eva Murray, a candidate in May's local government elections, stressed Labour had "never been a party of the status".

She told the audience: "We have always argued and strived for more, to ensure that working people's voices are heard, and not just heard but listened to and acted upon.

"That is why we as a movement are committed to strengthening our national Parliament at Holyrood, but at the same time devolving power down to our councils and empowering local communities in the process."

She said Labour had delivered devolution to the different parts of the UK and "must now continue what we started".

On the party's plans for a more federal UK, she argued: "This is not just a simple answer to the constitutional question we, of course, need an answer to, but also a bold vision for the sort of Scotland and UK we should all be striving towards."

Ms Murray added: "When the SNP and Tories again put their own party interests over the needs of Scottish people, Scottish Labour must once again step up and find a solution."

Labour councillor Lesley Brennan also spoke in support, saying: "We must be championing a radical federal structure to ensure nations and regions have the powers necessary to to bring about radical political responses to meet local needs."

Pauline Brown, an activist from Glasgow Kelvin, raised "one word of caution" over Ms Dugdale's call for a "new act of Union".

"I'm sure we can come up with a better thing to be campaigning for," Ms Brown said.

"We don't want a union of the crowns, we want a union of the people.

"It's not so much constitutional change that we are arguing for, but political change, and that just can't be legislated for.

"It's got to be built from the ground upwards. It's got to be done through hard political struggle."