Theresa May has slammed the Red Cross description of a "humanitarian crisis" in the NHS as "irresponsible" and "overblown".
In angry exchanges during Prime Minister's Questions, Jeremy Corbyn had accused the Prime Minister of being "in denial" over the extent of the challenge facing the health service.
He said she had ignored doctors, who have warned "patients' lives are being put at risk".
Mrs May hit back at the charity over its criticism as the Government faces intensifying pressure to take action to tackle the problems facing the health service.
She said: "... we've all seen humanitarian crises from around the world and to use that description of a National Health Service, which last year saw two-and-a-half million more people treated in A&E than six years ago was irresponsible and overblown."
Earlier, Mr Corbyn had challenged her over the 485 patients forced to wait more than 12 hours on trolleys in hospital corridors last week - three times more than in the whole of January last year.
Labour MP Yvette Cooper responded by tweeting about the figures: "So Theresa May thinks this is only 'a small number of incidents'."
The Prime Minister has held the line that it is "not unusual" for there to be pressures on the NHS over winter and the Government had provided £10bn extra funding for the health service, a figure which has been widely disputed.
She said: "The Government has put extra funding into the health service... 2,500 more people are treated within four hours every day in the National Health Service - that's because of the Government putting in extra funding and the hard work of medical professionals."
Mark Porter, chairman of the British Medical Association's council, said: "The Government is wilfully ignoring the scale of the crisis in our NHS.
"Trying to play down the pressure that services are under shows the Prime Minister is out of touch with patients and frontline staff who are working flat out under impossible circumstances."
Mark Holland, president of the Society for Acute Medicine, said: "We are sadly becoming immune to the inadequate responses of our Prime Minister.
"It is truly shocking that our nation's leader chooses to ignore a unified message from multiple respected bodies. The Prime Minister continues to use isolated statistics to articulate a jaundiced interpretation of the truth."