Thousands of patients waiting for surgery are being sent home from hospital because there are no clean instruments available for doctors to operate with.

A survey of NHS trusts has shown a 40 per cent rise in the number of cancelled operations because of a lack of properly sterilised surgical equipment. And some patients who have already been prepared for surgery have been sent home after doctors discovered scalpels containing spots of blood.

Conservative MPs have blamed the shortage of sterilised equipment on a lack of government funding. They say cash-strapped hospitals have been sharing the cleaning of instruments with others in order to save money.

A survey of NHS trusts by Grant Shapps, Conservative MP for Welwyn Hatfield, has shown that more than 1,700 operations have been cancelled this year because instruments were not clean enough.

The MP said that he had been prompted to conduct the nationwide survey after being contacted by a number of constituents who had been sent home because surgeons had no instruments with which to operate.

Among them was Brenda Harris, 40, who was told in her hospital bed that a hysterectomy for which she had been waiting eight months would have to be cancelled because the surgeon's instruments were dirty. She even offered to fetch clean equipment.

She said: "I went into hospital in Welwyn Garden City at about 7.50am and was found a bed. An anaesthetist and two doctors came round. I was told I would be going down about half past two. I hadn't eaten since 7am. At 5.20pm, a junior doctor said my operation had been cancelled due to unsterilised instruments. I was furious. I had been waiting months for this operation.

Trusts which responded to Mr Shapps's survey reported that there were 1,252 cancelled operations in 2002-03 due to equipment problems, rising to 1,765 in 2005-06.

The Department of Health said that it was a matter for NHS trusts to decide how to run their operations. But it said there had been a sharp overall drop in the number of cancelled operations.