LONDON (BLOOMBERG) - A delayed response by the British government to the coronavirus pandemic has left the health system "wholly unprepared" for an expected surge of critically ill patients, according to the editor of the medical journal The Lancet.

In a letter posted on the journal's website, Dr Richard Horton described chaos and panic across the National Health Service, basing his comments on messages he received from workers.

The government last month should have expanded testing capacity, ensured the distribution of protective equipment and stepped up training, he said.

"They didn't take any of those actions," he wrote.

"Patients will die unnecessarily. NHS (National Health Service) staff will die unnecessarily. It is, indeed, as one health worker wrote last week, 'a national scandal'. The gravity of that scandal has yet to be understood."

Hospitals across Britain are raising their defences ahead of a potential onslaught of coronavirus cases in a bid to avoid the toll seen in Italy, which has reported the most deaths worldwide.

While Dr Horton and other critics have sounded the alarm in recent weeks, the government has imposed the tightest restrictions on the movement of people that the country has faced in peacetime.

Britain's quarantine and social distancing measures should help keep intensive-care capacity from being overwhelmed, according to Professor Neil Ferguson, an Imperial College London researcher who makes mathematical projections of viral outbreaks.

Pressure on ICUs should peak in about two to three weeks, and some hospitals will be more strained than others, he told a parliamentary committee Wednesday.

Staff at the publicly funded NHS have expressed growing concerns in recent days over a lack of equipment and other measures to bolster the system's defences.

Responding to a survey by Britain's Health Service Journal, 34 chiefs of NHS trusts flagged concerns around a lack of staff, testing and personal protective equipment. One executive said the issue had caused a "near revolt" by employees, while at least a third reported that they would soon run out of intensive-care capacity.

Britain has confirmed almost 12,000 infections and about 580 deaths.

Adding to the uncertainty over the British government's response to the coronavirus, Prime Minister Boris Johnson on Friday became the first world leader to say he has tested positive.