Many of the trusts ranked bottom of the government's NHS performance tables have hit out at their low ratings.

A total of 10 NHS trusts - eight acute and two community trusts - in England received a zero star rating this year.

The trusts will be given a strict timetable to turn their services around or face being taken over by outside managers.

Zero star trusts

Bedford NHS Trust Bedfordshire and Luton Community Health Trust Barnet and Chase Farms Hospitals NHS Trust Hinchingbrooke Healthcare NHS Trust Portsmouth Hospitals NHS Trust Royal United Hospital Bath NHS Trust South Warwickshire General Hospitals NHS Trust South Warwickshire Combined Care NHS Trust United Bristol Healthcare Trust Weston Area NHS Trust

However, managers at these hospitals have suggested the data is out of date and does not reflect progress made in recent months.

The tables show that three trusts - Barnet and Chase Farm Hospitals, United Bristol Healthcare, Portsmouth Hospitals - are still among the worst in the country.

They each received no stars last year and have failed to win any this year either.

Two trusts - Royal United Hospitals Bath and Weston Area - have dropped from a one star rating to zero.

But three trusts - Bedford, Hinchingbrooke and South Warwickshire - have seen services deteriorate even further.

They were each awarded two stars last year but have now slumped to the bottom of the table.

Reliability doubts

Managers at these hospitals have questioned the reliability of the ratings.

Helen Nellis, chairwoman of Bedford Hospitals NHS Trust said: "The government star ratings are a reminder of where we were, not where we are or where we are going."

The trust's chief executive Andrew Reed said: "We have a programme of reform in place to make our processes more robust. Inevitably this has led to a period of transition while these measures take hold."

Managers at Hinchingbrooke Hospital blamed a critical report from the Commission for Health Improvement on its poor rating.

A new team was recently brought in to run the trust. In a statement, they said: "A poor CHI report automatically results in a trust receiving a no star rating. Many of the issues identified by CHI have already been tackled and resolved."

South Warwickshire Trust also blamed a critical CHI report for its ratings.

It chief executive Chris Hegginbotham told BBC News Online: "By and large the indicators show we are middle of the range. But a critical CHI report means we automatically get no stars."

Managers at United Bristol Healthcare NHS Trust blamed financial difficulties, staff shortages and a lack of beds for their continued zero star rating this year.

Trust chairman Phil Gregory said: "We are not short of clinical or managerial capability, but beds. Our star rating reflects historic under-investment, rather than current performance."

The new management team at Portsmouth General Hospital NHS Trust said progress was being made. The trust was 'franchised out' after its no star rating last year.

But chief executive Alan Bedford said: "The Trust has turned the corner. We will get the basics right and our clinical services will continue to improve."

Commission under fire

However, another franchised trust, Barnet and Chase Farm, said its continued no star rating was also down to a critical CHI report.

Chief executive Paul O' Connor said: "We have improved our performance significantly since last year and are acting on CHI's findings."

Roger Moyse, chief executive of Weston Area Health, which lost last year's single star, also blamed CHI.

"We believe we would have done better but for that assessment," he said.

"Over the last six months we have made enormous progress on the action plan agreed with CHI."

Two community trusts - Bedfordshire and Luton and South Warwickshire Combined Care - were ranked worst in the first assessment of these types of hospitals.

The South Warwickshire has recently been taken over by the local primary care trust.

In a statement, managers said the low ranking reflected "failures in financial administrative services".

However, they added: "The clinical indicators show that patients are receiving high quality services and staff welfare is given top priority.

Under government plans, failing trusts will be required to draw up action plans to improve services and overall performance.

Those trusts where managers have not yet been replaced will be given three months to show signs of improvement.

If they fail their management will be franchised out and a new team will be brought in.

Those trusts that have seen management franchised out will have another 12 months to show significant improvement.