NHS bed occupancy rates soared above safe levels for the first three months of this year, official figures show.
Experts say that if more than 85% of beds are being used then patients can be exposed to risks.
But the latest data from NHS England shows that, on average, almost 90% of beds were full during January, February and March.
During the last quarter of 2012/13 the average occupancy rate for general and acute overnight beds was 89.7%, NHS England said.
The figure has risen slightly for the last three years - during the first three months of 2011 the average occupancy rate stood at 88.7% and in 2012 it was 89%.
Healthcare information firm Dr Foster, which the government half owns, says that when occupancy rates rise above 85% “it can start to affect the quality of care provided to patients and the orderly running of the hospital.”
And research undertaken in 1999 concluded that “risks are discernible when average bed occupancy rates exceed about 85%”.
A British Medical Association spokesman said: “There is evidence that high rates of bed occupancy contribute to hospital acquired infections like MRSA and Clostridium difficile (C.diff).
“Efforts to improve infection control through hygiene measures such as hand-cleaning and antibiotic usage will be undermined if we don’t address the high turnover of NHS beds.”
Earlier this week Labour warned that hospitals are ”dangerously close to full” after it emerged that the number of hospital beds available to patients in England has shrunk by almost 6% since the coalition government took office.
Over the last 25 years the number of general and acute beds available in the health service has shrunk by 41%.
In 1988 there were 181,000 beds available to patients but now there are just 106,000.
A Department of Health spokeswoman said: “”Bed occupancy rates fluctuate slightly but have remained broadly stable since 2000.
“The NHS needs to manage beds effectively in order to cope with peaks in demand. There are higher occupancy rates in winter, when demands are at their greatest.
“Bed availability fluctuates but the NHS has practice and experience in managing capacity to cope with both routine and emergency care.”
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