Two more UK hospitals are bringing back masks for staff and visitors amid a sharp rise in flu cases.

Wexham Park Hospital in Slough, Berkshire, and Frimley Park Hospital near Camberley, Surrey, will announce the change on Tuesday, the BBC understands.

Frimley Health NHS Foundation Trust, which runs the two sites, said the number of patients with flu had doubled in the last two weeks.

It said there had been outbreaks on wards and the dominant strain was “particularly virulent”.

The flu season has arrived earlier than normal in the UK and has not yet peaked, the government has previously warned.

The rate of flu hospitalisations in the last week of November was 63% higher than the week before, according to the UK Health Security Agency.

Several hospitals have been put under strain and have reintroduced masks, including at Guildford’s accident and emergency department.

Frimley Health NHS Trust said it would supply masks for staff on clinical wards and for visitors at the hospital entrances.

Extra hand gel dispensers will also be provided, the trust said.

It said the current H3N2 strain of flu could cause severe symptoms for a week, even for some patients who are already vaccinated.