The Prime Minister should be given the power to appoint the most senior civil servants who run Whitehall departments, a Government-commissioned report has recommended.

The IPPR think-tank said Cabinet ministers should also be able to appoint an "extended office" of staff who work directly for them comprising political advisers and non-partisan outside experts as well as career civil servants.

The proposals are intended to make officials more accountable and responsive to ministers without undermining the commitment to a non-partisan, merit-based civil service. They are likely, nevertheless, to prove highly contentious and provoke fresh accusations that ministers are trying to politicise Whitehall.

Under the IPPR plan, the recruitment process for permanent secretaries who run Government departments would still be overseen by the independent Civil Service Commission which would be responsible for drawing up a short list of suitable candidates.

However, the final selection would be made by the Prime Minister who, the report argues, is best placed to pick the key personnel who are needed to ensure the successful delivery of his political programme.

The successful candidates would be given fixed-term four-year contracts which would be renewable depending on performance.

Cabinet Office Minister Francis Maude, who commissioned the report, welcomed the proposals, describing them as "evolutionary" and saying they went "with the grain of our Westminster system".