Health inspectors announced a "blitz on hospital cleanliness" last night in response to mounting public alarm about the spread of the MRSA superbug and lack of basic hygiene in many wards and casualty departments.

For the first time, they will mount random spot checks on 100 hospitals in England over the summer to check whether hospitals are meeting the recommended standards of hygiene. The Healthcare Commission said the special round of inspections would cover acute, community and mental health hospitals in the NHS and independent sector. Most unannounced visits will take place at places identified as poor performers in the past.

The inspections will focus on cleanliness of areas used by patients and the public, including wards, outpatient areas and emergency departments. They will be assessed against a checklist of 55 standards of cleanliness. Findings will be published in the autumn.

Patricia Hewitt, the health secretary, is planning to intro duce legislation later this year giving the commission powers to issue improvement orders to dirty hospitals. Chief executives failing to implement such instructions would become liable to criminal prosecution.

Last week, she asked the commission to investigate the spread of the infection, Clostridium difficile, at Stoke Mandeville hospital, Oxfordshire, where it has claimed 12 lives. This week, she is due to publish the latest national MRSA infection statistics amid evidence that patients are starting to avoid going into hospital for necessary treatment for fear of getting infected.

Anna Walker, the commission's chief executive, said: "Patients and the public tell us they are concerned about cleanliness. There is a real danger this issue could damage confidence in healthcare.

"But there is a shortage of facts, and this exercise is about getting those facts."

Links between poor hygiene and the spread of hospital-acquired infections will be studied in a separate, three-year improvement review of healthcare infection and control, starting later this year.