A government claim that every hospital has passed food and hygiene checks was dismissed yesterday as "untrustworthy".

Patients' groups and opposition parties said the Department of Health ratings, which were introduced two years ago, bore no resemblance to the reality of patients' experiences.

The department has implemented a "traffic light" system for rating hospitals on food quality and overall cleanliness. As with last year, all hospitals were given an amber "acceptable" or green "good" rating for cleanliness. It is the second year running there have been no red "poor" ratings on hygiene.

Food quality also improved. Last year, 14 hospitals were rated as poor for the state of their menus; this year, all were either amber or green. Patients' groups and the Tories said the ratings were not borne out by the experiences of patients.

Liam Fox, the shadow Health Secretary, said: "Everybody knows that you cannot trust the Department of Health's statistics assessing its own performance when they are created by the department itself. The ratings bear no relation to the quality of care that patients receive."

The Government has spent £34m on its better hospital food programme, which has included recruiting the celebrity chef Loyd Grossman to improve menus. The old system of meat-and-two-veg lunches has been replaced with daytime snacks, curries and risottos. A further £68m has been invested in the clean hospital programme.

Lord Warner, a Health minister, said: "Standards of cleanliness and food are continuing to rise. There is still more to do before we provide the high standards which always meet patients' needs and generally exceed their expectations, but these latest results show that we have made progress towards consistently high-quality hospital food services that are well regarded by patients."

The Liberal Democrats revealed earlier this year that out of the 40 hospitals with the most MRSA or "superbug" cases, none was classed as a "dirty" hospital under the ratings system. Evan Harris, the party's health spokesman, said: "The clean hospital programme should be prosecuted under the Trade Descriptions Act. It is nothing of the sort. It covers different standards of which only one is about cleanliness and none is about the control of infection."

Research into MRSA by the Tories found that of the 20 worst hospitals for the superbug, 15 were rated as good and the other five acceptable.

Lord Warner insisted that MRSA was a "different issue to general cleanliness". He said: "MRSA is a problem across Western Europe and America. All advanced countries have problems ... it is not particular to this country."