By Jonathan Davies

The Deputy Prime Minister Nick Clegg has given his backing to a "radical" new report calling for devolution of powers to English regions.

The report, published by think tank IPPR North, says some local authorities should be merged and headed by elected "metro mayors".

Nick Clegg said the debate over Scottish independence has raised the issue of devolution of powers in England. The three main political leaders, David Cameron, Ed Miliband and Nick Clegg, all travelled to Scotland this week to promise greater devolved powers for Holyrood if the Scottish public choose to remain part of the UK.

The report, titled 'Decentralisation Decade', claims that just one of the biggest economies outside of London achieve the average GDP or higher.

Birmingham, Leeds, Liverpool, Newcastle, Nottingham, Sheffield and Manchester have lagged behind the national average GDP per capita. Only Bristol has bucked the trend.

The report highlights countries like Germany, Sweden, Italy and France where "so-called second-tier cities have been at the forefront of economic growth".

IPPR North recognised the efforts of the government to decentralise power through things like the City Deals, free schools and Police and Crime Commissioners, but also highlighted 40 different government functions, which are currently controlled by 13 Whitehall departments, that could be devolved to local authorities.

Deputy Minister Nick Clegg said: "If ever there was a time to push for action on decentralisation, it's now," he is expected to say.

"You only need look at how the Scottish Referendum debate has re-energised people's interest and engagement in politics over the last few weeks to see that this is an idea whose time has come."

Shadow Communities Secretary Hilary Benn said: "There is now an unstoppable tide running in favour of passing power down, but Nick Clegg seems to be waking up late to the call for less centralisation.

"What people want is not warm words but substance to back it up."