The Government has yet to spell out details of £38 billion of spending cuts which would have to be imposed after the general election to meet Chancellor George Osborne's plan to eliminate the deficit without tax rises, an influential economic think tank has warned.

The warning from the Institute for Fiscal Studies (IFS) came after the Financial Times calculated that Mr Osborne's austerity target would require cuts of £48bn in services such as the police, courts and armed forces.

The IFS said Labour had yet to provide details of tax rises or cuts in welfare and spending it would impose to achieve its goal of getting the current account deficit into surplus over the course of the next Parliament.

Prime Minister David Cameron said the Government had made £100bn savings in this Parliament.