A Tory peer who branded nurses as "grubby, drunken and promiscuous" during a Lords debate was facing a backlash yesterday, with nurses' leaders describing his comments as grossly unfair and calling for him to produce evidence to back up his claims.

Lord Mancroft told peers it was a miracle he was alive after his experience of filthy wards and "slipshod and lazy" nurses at the Royal United hospital, Bath. During the debate on Thursday night he claimed the nurses had openly chatted to one another about their sex lives and alcohol intake in front of patients, some of whom they regarded as "a nuisance".

"The nurses who looked after me were mostly grubby - we are talking about dirty fingernails and hair - and were slipshod and lazy. Worst of all, they were drunken and promiscuous," he said, adding that the nurses were "an accurate reflection of many young women in Britain today".

The Royal College of Nursing (RCN) said his comments were an attack on nurses across the UK and amounted to a "sexist insult" against all British women. The RCN general secretary and chief executive, Peter Carter, said: "If any patient has an issue with their treatment by staff they should raise this with the healthcare provider, rather than make sweeping generalisations about nurses and sexist insults about the behaviour of British women."

The peer, who lives in Badminton, Gloucester, was admitted to the Royal United for a week last August, with what is believed to have been an intestinal infection. During the debate he described the experience as appalling.

"If you are a patient and lying in a bed and being nursed from either side, they talk across you as if you're not there. So I know what they got up to the night before, how much they drank and what they were planning to do the next night. I can tell you it's pretty horrifying. I can only tell you that it is a miracle that I am still alive. The wards were filthy."

Francesca Thompson, director of nursing at the hospital, said: "We excel at our job and his comments have devastated our staff. He's made serious allegations in a forum where we had no chance to respond."

James Scott, chief executive of the RUH, revealed he had quizzed Lord Mancroft about his claims and demanded evidence of any wrongdoing. "I hope Lord Mancroft will now reflect on the damage he has done to the general reputation and moral standing of the nursing profession."

Don Foster, Liberal Democrat MP for Bath, demanded Lord Mancroft withdraw his claims if he could not back them up.

The health minister, Ann Keen, said: "The country holds nurses in the highest regard. People will want to know what action David Cameron is taking on this matter or if he shares his views."