Gordon Brown supports Dugdale's call for new Act of Union
The former prime minister said Labour could chart a third way between independence and Brexit.
Gordon Brown has thrown his support behind proposals to move towards a federal UK.
The former prime minister praised a speech by Kezia Dugdale on Wednesday in which the Scottish Labour leader called for a new Act of Union to safeguard Scotland's place in the UK and the EU.
Dugdale told the Institute for Public Policy Research, a left of centre think tank, that a constitutional convention and further devolution to Scotland and the English regions were needed in light of Brexit.
The blueprint will be presented to the next Scottish Labour conference for the approval of party members.
Speaking on Thursday, Brown said: "The Scottish Labour conference in February 2017 can be a milestone event in the recovery of Labour.
"Kezia Dugdale's decision to put to the Labour Party membership her new constitutional reform programme should be welcomed by all members.
"Her proposals to extend the powers of the Scottish Parliament, reaffirm Scotland's leading role in the United Kingdom and establish a UK-wide constitutional convention deserve widespread public support.
"They offer a bold solution with the repatriation of European powers to Scotland and a more federal constitution for the UK."
He added: "The SNP wants Scotland in Europe but not in Britain, while the Conservatives want Scotland in Britain but not in Europe.
"In place of these two extreme positions in the post-Brexit debate - all-out independence or hard Brexit - Labour's proposal would not only give Scotland a new role in both Britain and Europe but is also the best way of meeting the challenges that really matter to the Scottish people - enabling us to tackle poverty, reduce inequality, guarantee high quality public services and secure full employment."
The former MP for Kirkcaldy and Cowdenbeath followed his fellow Scot Alistair Darling, who backed the Dugdale proposals on Wednesday.
Darling, who served as Chancellor of the Exchequer during Brown's premiership, said: "As poll after poll shows, a clear majority of Scots want to remain in the United Kingdom. But we need to strengthen that union with a new settlement.
"One that reflects the need to devolve more power across the UK and to make the responsibilities of the UK Parliament and the devolved parliament and assemblies clear.
"We need to strengthen our constitutional settlement and I fully support Kez's proposal. For too long this has been dismissed as too difficult. It isn't. A convention can deliver the settlement the whole country now needs."
Addressing public policy analysts and journalists in London on Wednesday, Dugdale advanced Scotland's experience with devolution as an example to be drawn upon in seeking to refashion the UK as a federal state.
She told her audience: "The time has come for the rest of the UK to follow where Scotland led in the 1980s and 1990s and establish a people's constitutional convention to re-establish the UK for a new age.
"The convention should bring together groups to deliberate on the future of our country and propose a way forward that strengthens the UK and establishes a new political settlement for the whole of our country.
"This is a convention that the government should convene, and I have written to Theresa May today outlining Scottish Labour's desire to see this happen.
"However, if the government is not willing, as Gordon Brown has said, the opposition should convene a convention."