Shadow defence secretary Jim Murphy has said Labour will accept £5bn of the government's planned defence cuts and urged his party to avoid "populist" opposition to necessary austerity measures.

"It is important to be both credible and popular when it comes to defence investment and the economics of defence," Murphy told The Guardian.

"There is a difference between populism and popularity. Credibility is the bridge away from populism and towards popularity. It is difficult to sustain popularity without genuine credibility. At a time on defence when the government is neither credible nor popular it is compulsory that Labour is both."

Among items he said the opposition would accept were the scrapping of the Nimrod MR4 surveillance aircraft, efficiencies in the renewal of the Trident nuclear deterrent, a slimmed down defence estate, cuts to civilian allowances and reducing tank regiments.

But he indicated that he would maintain opposition to other high-profile changes such as the lack of an aircraft carrier capability for up to a decade.

Economic Secretary to the Treasury, Chloe Smith said: “After a series of attacks on his weak leadership, this is the latest blow to Ed Miliband as even his own Shadow Cabinet are losing confidence in Labour’s economic policy.

“Until Labour say what spending they would cut to clear up their mess, rather than calling for more spending, more borrowing and more debt, they will never be trusted with our economy again.”