Opposition parties have seized on the news that the number of last minute operation cancellations increased by almost a quarter in the first three months of 2005.
The Conservatives said it was "unacceptable" and the Liberal Democrats warned it may only be the tip of the iceberg.
There were 21,566 cancelled operations for non-clinical reasons between January and March - 24 per cent more than in the last three months of 2004.
These figures represent the second successive quarterly rise in operation cancellations, yet Health Minister Lord Warner played down their significance.
"Since 2001, the number of last minute cancellations, as a percentage of operations carried out, has fallen. This is even against a backdrop of increased activity in the NHS," he said.
"Almost 99 per cent of operations, some five and a half million, are carried out on time. But obviously one cancellation is one too many and, as capacity increases, the NHS is working hard to ensure all patients are seen on time," Lord Warner added.
The increase in cancellations is partly a result of the fact that demand for hospital beds increases during the winter months, often causing cancellations as there is not the space for patients to recover.
However the Government is keen to reduce cancellation rates and may effectively fine hospitals for cancelling surgery without offering an alternative date.
There were 17,402 operation cancellations between October and December 2004 and 14,931 between July and September.
Shadow Health Secretary Andrew Lansley put the blame on hospital targets.
Mr Lansley said: "It is unacceptable given the amount of money spent in the NHS, that the number of cancelled operations is so high. Many operations are cancelled last minute because of Labour's targets: the six month inpatient waiting list target, the overall waiting target, or the four hour A & E target. Conservatives would abolish all such targets imposed on hospitals."
Lib Dem health spokesman Steve Webb said that the figures were "shocking" and also pointed to targets as a problem, saying: "Hospitals are under severe pressure to meet targets and push more and more patients through the system, and inevitably this impacts on quality of care."
And he added: "But Government statistics do not tell the whole story. Many people have their operations cancelled the night before they are due to go in for their operation, but these cases are not recorded in the official figures.
"The Government should undertake an urgent investigation to find out whether these figures are only the tip of the iceberg."