LABOUR was last night accused of wasting taxpayers' money on "rearranging the deckchairs of the Titanic" as a damning report revealed more than £780 million has been spent on Whitehall shake-ups.

The National Audit Office said the enormous bill had been run up in just five years, with first Tony Blair and later Gordon Brown rushing into reorganising government departments and agencies with little public benefit.

Critics claimed only the logo designers and makers of nameplates were the obvious beneficiaries of the relentless makeovers.

It is impossible to demonstrate that the changes made since the 2005 General Election offered value for money, the NAO said – a situation it branded "unsatisfactory".

The break-up of the Department for Environment, Food and Rural Affairs – which saw responsibility for climate change hived off to a new ministry – is singled out in the report. The government said the new Department for Energy and Climate Change was needed to "provide more joined-up policy" and to "send a clear message to consumers, energy consumers and other governments on the strategic importance of this issue".

But at the same time other public bodies were being merged, claiming closer working would cut costs through fewer senior managers, shared infrastructure and property and efficiency savings.

Tory MP Geoffrey Cox, a member of the Commons select committee which probes Defra's work, said: "We have the biggest national debt in our history and the government is running around rearranging the deckchairs on the Titanic, spending hundreds of millions of pounds of taxpayers' money."

The Torridge and West Devon MP added: "It reflects what this government has been all about – concentrating on the supercritical at the expense of what really matters."

But while new bodies were being created, others were being merged. Overall, the NAO said there was no requirement to show that the reorganisations were "sensible" and they may simply have been "unnecessary".

Central government bodies had proved "very poor" at identifying the costs of reorganisation and were "weak" when it came to securing the hoped for benefits of change.

South West Devon Tory MP Gary Streeter said: "This government has restructured much and delivered little."

In all, it said that there had been more than 90 reorganisations of central government departments and their associated "arm's length" agencies between the election in May 2005 and June 2009.

Of the 51 reorganisations examined by the NAO during that period, it put the cost at £780 million – an average of £15 million for each reorganisation and the equivalent of almost £200 million a year. A total of £33 million had been spent on "branding and communications".

Edward Leigh, the chairman of the Commons Public Accounts Committee which oversees the work of the NAO, said it was hard to believe that all the changes actually served the interests of the public.

Two of the new departments created since Mr Brown became Prime Minister in 2007 – the Department for Business, Enterprise and Regulatory Reform and the Department for Innovation, Universities and Skills – lasted less then two years.

A Cabinet Office spokesman said that work was already under way to streamline the number of arm's length bodies and improve the process for making changes to the machinery of government.

"Value for money must always be a priority, but it is also important that the Prime Minister is able to structure the Government, acting quickly if necessary, to best develop and implement the Government's policies and deliver on key priorities that bring real benefits to people and public services," the spokesman said.