The former Tory leader launched a scathing attack on the corporation, and singled out economics editor Stephanie Flanders for the harshest criticism, accusing her of "peeing all over British industry".

BBC officials last night defended the organisation's record of impartiality and Ms Flanders's reporting.

But Mr Duncan Smith claims the broadcaster diminishes the role of the Government in good news stories but "dumps" on it when the story is bad.

The minister appeared to be particularly angered by coverage this week of unemployment figures after there was an unexpected drop in Britain's jobless.

His department has formally complained to head of news Helen Boaden over the broadcaster's "carping and moaning".

He told a Sunday newspaper: "The BBC is locked to the reading of the economy that is run out of Ed Miliband and Ed Balls's office. They think if only you spend and borrow more money you can create growth. They expected the figures to be flatlining. They convinced themselves youth unemployment would continue to rise, but when it fell they were in a quandary.

"Stephanie Flanders poured cold water over the whole thing. She said: 'Of course this is good news, but it could be because we aren't productive enough'."

Mr Duncan Smith added: "If the unemployment figures had gone up, we would have been on the BBC TV News at Six and Ten and would have got the blame."

A BBC spokeswoman said: "BBC News is confident our coverage of this story was impartial, fair and balanced, reflecting a wide range of views. Stephanie interrogated numerous aspects of the figures in her analysis."