More than 750 St John Ambulance volunteers have offered to help at the new hospital set up to meet demand for intensive care beds as the coronavirus crisis escalates.

Up to 200 first aiders per day will assist at the Nightingale hospital set up in London’s ExCeL centre, which is ordinarily used for exhibitions and trade fairs. The volunteers will be needed day and night, with 100 on each shift.

The 143-year-old charity has some 8,500 regular volunteers and often provides an auxiliary ambulance service at public events.

The volunteers are undergoing selection procedures and getting further training. They could be in the field caring for coronavirus patients as early as next Wednesday, the organisation said. Many others will be assisting in other makeshift centres set up in different parts of the country.

Richard Lee, the charity’s chief operating officer, said: “In the coming weeks and months, St John Ambulance will face extraordinary demands, the likes of which our organisation has not faced in peacetime. Our resources will be stretched, and our people will be tested, but we will stop at nothing to help beat this virus.”

St John said it was in the midst of an “unprecedented” training push of more than 1,000 volunteers to ready them for frontline work alongside NHS staff as the pandemic deepened.

Ruth May, the NHS’s chief nursing officer for England, said she was “delighted” at the charity’s offer of help, adding: “We cannot win this battle against the virus alone.”

She also urged any former NHS clinical staff who have not yet done so to respond to the Your NHS Needs You recruitment campaign. “Given the scale of the task ahead we cannot have too many doctors, nurses or other health care staff.”

Meanwhile, it emerged late on Saturday night that David Lloyd Clubs is in talks with the government about converting a “handful” of its largest gyms into emergency medical facilities, according to ITV News.

The clubs are not currently in use as Boris Johnson ordered leisure centres and gyms to shut their doors during the lockdown. A spokesman for the fitness group confirmed discussions were under way, ITV News said.

The NHS will build more temporary hospitals in Birmingham, Manchester, Cardiff and Scotland. The National Exhibition Centre in Birmingham will add an initial 500 beds, with the potential to grow to 2,000 if necessary.

Manchester Central Convention Complex will add another 500, with the capacity to expand to 1,000, and Cardiff’s Principality Stadium will provide up to 2,000 more.