The Institute for Public Policy Research (ippr) said Health Secretary Patricia Hewitt should be stripped of the power to approve changes or refer them to an independent panel.

Instead, local authorities should be allowed to call directly on the Independent Reconfiguration Panel (IRP) to examine so-called "reconfiguration" decisions such as closures.

So far, 23 decisions have gone to the Secretary of State from local overview and scrutiny committees - with four referred on to the IRP.

Claims of political interference in the process flared up last year amid suggestions that changes were being manipulated to help Labour in marginal constituencies.

The ippr report said the medical evidence for the reorganisation was so overwhelming that the public should really be on the streets campaigning for the changes, not against them.

More than 1,000 people could die unnecessarily every year if campaigns to retain some services in district hospitals instead of being centralised were successful, it suggested.

Research showed heart attack victims and the severely injured were more likely to survive if treated in specialist centres

Richard Brooks, ippr head of public services, said: "Hospitals need to change. On the strength of the clinical evidence, people should be out on the streets campaigning for changes to NHS services to protect the health of their families, not to keep services the way they are.

"But the decisions about what hospital wards and services are affected should not involve ministers in Whitehall. At the moment, vital hospital changes are being opposed because the public believe they are politically motivated or driven by cost-cutting. We do need the Government, in partnership with clinicians, to set the policy framework, but then ministers should have no say in the final decision."