Left-leaning Labour activists have urged the party to "go further and faster" with its policy for constitutional change.

The Red Paper Collective will launch its Progressive Federalism paper at the Scottish Labour conference in Perth this weekend.

Scottish Labour leader Kezia Dugdale set out her plan for a new Act of Union, with increased powers for Holyrood, Cardiff Bay, Stormont and the English regions, in December.

She advocated transforming the UK into a federal system and called for a ''people's constitutional convention'' to decide on a ''new political settlement'' for the whole country.

Read more: Scottish Labour donations collapse in Dugdale's first year as leader

UK leader Jeremy Corbyn backed the notion of a constitutional convention for the whole of the UK but rejected the idea of a new Act of Union last month.

Scottish Labour is due to debate Scotland's place in the UK on the opening day of its conference on Friday.

The Red Paper Collective's work argues for federalism based on socialist values and includes contributions from MSPs Neil Findlay and Richard Leonard and MP Jon Trickett, who has been tasked with taking forward the party's plans for a constitutional convention.

Commenting ahead of publication, Mr Findlay said: "We need to be building a movement for radical constitutional change, but with the clear purpose that this will drive the economic and social change we want to see.

Read more: Scottish Labour donations collapse in Dugdale's first year as leader

"Post the Brexit referendum, the economic case for independence has become much weaker and with the repatriation of powers the case for federalism is stronger - now is the time for a genuine and credible alternative."

Pauline Bryan, convener of the Red Paper Collective said: "Having been arguing the case for a federal arrangement for some years now, we are pleased leaders of the Labour Party at UK and Scottish level have endorsed the idea of a constitutional convention and spoken favourably about a more federal UK, and that idea will be put to the Scottish Labour Party on Friday this week."

A spokesman for Scottish Labour said: "Kezia Dugdale's plan for a People's Constitutional Convention has strong support across the whole of the Labour Party, as this intervention shows.

"The majority of people in Scotland want us to remain in a reformed UK, where power and wealth are shared more equally across the country. Scottish Labour members and trade unionists will vote on our vision for a federal UK at the party conference on Friday.

Read more: Scottish Labour donations collapse in Dugdale's first year as leader

"The SNP must rule out another independence referendum and focus on the day job. Labour will not support any plans by the Nationalists to impose another independence referendum on the people of Scotland."