The Tories accused the Government of "pre-election trickery" after figures were released which ministers said showed infections by the hospital superbug MRSA had peaked.

Lord Warner, a Health minister, said figures from the Health Protection Agency, published yesterday, showed an overall fall of 6.3 per cent in MRSA cases last summer compared with the same period a year earlier.

Since 2001, when mandatory reporting of MRSA began, the trend had been upwards and this was the first sign of a reverse, with a new low of 3,519 bloodstream infections from April to September last year, Lord Warner said.

"I think it is a turning point. It shows the NHS is getting behind this agenda," he said. "But we are not trumpeting it. It is not the end of the story but it is a significant shift of direction by the looks of it."

The Tories said the figures were flawed as they failed to include the winter months, when rates were higher, and they only included bloodstream infections, not MRSA contracted through other means, such as open wounds after surgery.

Andrew Lansley, the shadow Health Secretary, said: "Blair's government has failed to make clean hospitals a priority. Suddenly, a few months before a likely election and eight years after no action, we get flawed figures that smack of pre-election trickery."

About 5,000 patients die each year from infections picked up on hospital wards, including about 1,000 from MRSA.