Handwashing is still key to reducing hospital infections

Assembly opposition parties had been calling for this data to be published.

But when unveiled on Thursday, the parties said they regretted the figures had only been made public under new rules on the freedom of information.

The assembly government had been reluctant to publish the figures until now because of their complexity.

The statistics confirm that Welsh hospitals perform better than their English counterparts on the whole but that some Welsh NHS trusts perform better than others.

Ceredigion fares best - with one case of MRSA per 33,000 bed days.

Swansea is one of the worst trusts statistically, with one case in every 5,500 bed days.

But both the assembly government and the hospitals themselves said the statistics alone did not tell the whole story.

Figures show Welsh hospitals have lower rates of MRSA infection

Swansea, for example, is designated a specialist trust. A spokesman said the patients treated there were therefore often more vulnerable to infection.

Velindre NHS Trust in Cardiff has the highest number of MRSA cases per 1,000 bed days, but a spokesman said the small size of the hospital meant there was a big scope for statistical error.

He added that the figures should be seen "in the context of our services", and that infection rates compared well with other specialist cancer centres.

'Hospitals are too dirty'

The assembly said it was these complications which made it reluctant to release trust-by-trust information, although Health Minister Brian Gibbons announced on Wednesday that he would be consulting soon on new ways to publish infection figures.

Liberal Democrat leader in the assembly Mike German said: "We didn't know the figures, the minister refused to give them to us.

"The Labour government here said these are matters for each local trust.

"Well, we've have now got the figures and what was the reason for keeping them secret?"

Plaid Cymru claimed the figures showed MRSA cases, though lower than in England, were on the increase.

Tory health spokesman Jonathan Morgan said: "More needs to improve hospital cleanliness. Hospitals are too dirty.

"People are going in with one illness and coming out with something quite different."

The assembly fovernment consultation on how to publish infection figures in future is due to begin in around a week's time.