LABOUR should do more to appeal to the middle classes, David Miliband has suggested in a move that will be seen by many as a parting shot against his brother's leadership of the party.

Left-wing parties had to do more to "protect" the so-called "squeezed middle", the elder Miliband, who is moving to America, indicated. "We… should take this challenge seriously," he added.

Among the steps he suggests include campaigning for higher wages and embracing austerity over the medium term.

His intervention follows a week of negative headlines over Ed Miliband's leadership.

A number of Labour MPs have spoken out to question where the party stands on issues such as welfare and warn that it risks losing the next general election.

Mr Miliband also condemned a "broken" political system which left parties under the control of small groups.

He quit as an MP for South Shields earlier this year to become president and chief executive of the charity International Rescue. The trade union bloc vote was crucial in denying him victory.

In the New Statesman, the elder Mr Miliband praised the "exemplary" open primary system which resulted in France's Francois Hollande being nominated as the socialist party's presidential candidate.

He said politics was "not merely seen as broken but actually broken", adding: "This is not just about corruption scandals. It is also about political systems that, for too many people, have lost their capacity to engage and include."

Conservative Party chairman Grant Shapps said: "Even David Miliband thinks Labour must change."