Labour must demonstrate it has credible policies to rebuild and grow the economy if it is to regain power at the next general election, a former senior policy adviser to the party has warned.

Patrick Diamond, who co-wrote the party's 2010 election manifesto with Ed Miliband, said it was no use Labour "promising the earth" if it did not have the means to deliver on its commitments.

While Mr Diamond, who worked in No 10 under Tony Blair and is a former adviser to Lord Mandelson, acknowledged the cost of living would be a central issue in the election, Labour needed to do more than simply promise to freeze energy prices.

"There is no point in politicians promising the earth, then failing to deliver. People want to know what Labour is going to do about living standards," he told the BBC Radio 4 Today programme.

"It has an energy price policy, it has a rail fares policy, but these are fairly incidental in the great scheme of things.

"The question people will be asking is 'does Labour have a plan to produce more high quality jobs, does it have a plan to raise wages, does it have a plan to attract competitive industries to the UK?'

"These are the issues that will in the long term determine the living standards of the British people."

His comments echo criticisms within the Labour ranks that while concentrating his fire on the "cost of living crisis", Mr Miliband has failed to develop a policy platform to address wider economic issues.

Those concerns have been heightened by official figures last week showing that increases in wages have edged above inflation for the first time in four years, suggesting Labour's message may start to lose its impact just as the election approaches next year.