Infections with the hospital “superbug” MRSA in England, which have been blamed in an increased number of patient deaths, have fallen to their lowest level in recent years, according to official figures on Monday.

But Health Secretary John Reid acknowledged MRSA “remains a problem” and announced the National Health Service would pilot a new rapid swab technique to identify patients with the bug within hours rather than days.

Opposition parties treated the figures with caution.

The Liberal Democrats said they did not tell the whole story and called for the government to publish what it called the facts about the true level of infection in the health service.

MRSA (Methicillin Resistant Staphylococcus aureus), which is resistant to drugs, can cause skin infections, sepsis and toxic shock. Hospitals have come under fire for slack hygiene and cleanliness standards.

The figures from April to September 2004 showed 3,519 NHS patients were infected with MRSA compared with 3,940 in the previous six months and 3,598 in the same period of 2001, according to the independent Health Protection Agency (HPA).

“These latest figures show MRSA rates at the lowest since mandatory recording began - something we introduced in 2001,” Reid said in a statement.

“But there is still much to do,” he added.

Liberal Democrat shadow health secretary Paul Burstow said reporting on MRSA only helps if it gives patients useful information and prompts staff to change the way they work.

“It is good news that the rate of MRSA infections is falling, but ministers would be wise not to see this as a turning of the tide,” he said in a statement.

Reid said the HPA would publish data on MRSA every six months from now on.