Rupert Murdoch berated Sun journalists for not doing enough to attack Ed Miliband and stop him winning the general election

Rupert Murdoch berated journalists on his tabloid papers for not doing enough to stop Labour winning the general election and warned them that the future of the company depended on stopping Ed Miliband entering No 10.

The proprietor of Britain’s best-selling tabloid warned executives that a Labour government would try to break up News Corp, which owns The Sun, The Times and The Sunday Times. He instructed them to be much more aggressive in their attacks on Labour and more positive about Conservative achievements in the run-up to polling day, sources told The Independent.

Mr Murdoch is understood to have made his views clear on a visit to London at the end of February, during which he met with senior Tories including the Conservative chief whip and former Times executive Michael Gove.

The News Corp boss, who has made no secret of his dislike of the Labour leader, told the editor of The Sun, David Dinsmore, that he expected the paper to be much sharper in its attacks on Labour.

A hint of his frustration was evident on Twitter when the News Corp boss wrote: “Cameron’s Tories bash vulnerable Miliband for months with no effect on polls. Need new aspirational policies to have any hope of winning.”

Two days after Mr Murdoch’s visit the paper devoted a two-page spread to the election – with the left-hand page containing a 10-point “pledge” to voters written by David Cameron. The right-hand side of the spread was an attack on Ed Balls under the headline: “I ruined your pensions, I sold off our gold, I helped wreck [the] economy, Now I’m going to put up your taxes.”

It is understood that Mr Murdoch reminded executives that Labour would try to break up News UK, which owns The Sun, The Times and The Sunday Times. The party has suggested that no owner should be allowed to control more than 34 per cent of the UK media, a cap which would force News UK to sell one of the titles.

It has also pledged to implement recommendations in the Leveson report for an independent press regulator backed by statute, bitterly opposed by Murdoch. Mr Miliband has made “standing up” to Mr Murdoch over the phone-hacking affair a central plank in his attempts to persuade voters that he is a strong leader. A source said: “Rupert made it very clear he was unhappy with The Sun’s coverage of the election. He basically said the future of the company was at stake and they need to get their act together.”

A spokesman for The Sun said: “As has always been the case, The Sun’s political coverage is informed by how the political parties approach the issues that matter most to our readers. The Labour Party has been weak on tackling the deficit, weak on immigration, weak on fracking and opposes giving the country a referendum on the EU. If Ed Miliband wants to ignore the concerns of Sun readers we feel it is our responsibility to reflect that decision.”

Labour has complained that the tone of The Sun’s coverage has become increasingly hostile. A party source said: “Every announcement we gave them got twisted.”

Mr Miliband was mocked-up as a character from The Simpsons, in a spread headlined MANIFEST-D’OH! last week. The paper also accused him of “hypocrisy” because he and his wife Justine use an upper-floor kitchen, while his sons’ nanny has a second in the basement.

Last night a Sun source denied corporate concerns affected editorial decisions – pointing out that it had labelled Mr Miliband “Red Ed” when he was standing for the Labour leadership.