Outbreaks of the potentially lethal hospital bug Clostridium difficile are not being reported by some hospitals, says the body monitoring infections.
The HPA says C. difficile outbreaks are under reported
The Health Protection Agency has told BBC File on 4 that some trusts do not notify the HPA about outbreaks.
And the agency's Professor Peter Boriello said there are no figures for deaths caused by the bug.
However health minister Andy Burnham denied there was a problem and said he had no evidence of under reporting.
Part of the HPA's remit is to protect communities from the outbreak of infectious diseases.
Professor Boriello, director of the HPA's centre for infections, said in some cases, trusts did not report outbreaks of C. difficile because they felt they were able to deal with the bug.
However part of the government's strategy to prevent the spread of disease is greater reporting of outbreaks of infection.
"Better reporting would give better outcomes in many cases," he told the BBC.
Professor Boriello also admitted the HPA did not have figures for the number of deaths the bug has either caused or contributed to.
"It is a bit worrying," he said.
While a recent report by the campaigning group the Patients Association suggested that three quarters of healthcare staff involved in infection control responding to an anonymous survey of said their trusts were not gathering the data the should about C. difficile.
Mr Burnham said government's measures were beginning to control infection levels.
He added that he was confident trusts were reporting outbreaks of the bug.
"We don't have evidence, if there is evidence about reporting we would want to see it," said Mr Burnham.
Hear the full story on Radio 4: File on 4 Tue 28 Nov 2006 GMT or online at the File on 4 website