Hospitals in Britain are facing a "worst case scenario" from a wave of super flu, healthcare bosses warned on Thursday, as flu hospitalisations jumped 55% in a week.

Health leaders have told people who feel ill to wear face masks when using public transport, while some hospitals are requiring masks be worn, and more people are being urged to book a flu jab as the virus sweeps through the country.

NHS England said that an average of 2,660 patients were in a hospital bed with flu last week, the highest ever level for this time of year, up more than half in a week, in what it described as an "unprecedented wave of super flu".

"The numbers of patients in hospital with flu is extremely high for this time of year," Professor Meghana Pandit, NHS National Medical Director, said in a statement.

"Even worse, it continues to rise and the peak is not in sight yet, so the NHS faces an extremely challenging few weeks ahead."

Europe as a whole has been grappling with an unusually early and severe flu season, with health authorities across the continent warning of rising cases driven by a mutated strain of the flu.

The European Centre for Disease Prevention and Control said last month detections were rising "much earlier than usual" and urged vulnerable groups to get vaccinated "without delay."

In Britain, a planned five-day strike by resident doctors - qualified physicians who make up nearly half of the medical workforce - is due to start on December 17, adding more pressure to an already stretched healthcare service.

To try to stop the strike, health minister Wes Streeting presented the union with a new package of working conditions on Wednesday, which they are currently considering.