"This might be distasteful to some, but in many cases it would be necessary," said Dr Ron Daniels, founder of the UK Sepsis Trust and an intensive care consultant at the Heart of England NHS Foundation Trust.

"If, for example, you have the 90-year-old wife of an elderly man dying from coronavirus, you don't want to bring her into that environment.

"That would be a risk to her, and potentially to the critical care staff on the ward.

"If, however, you're talking about a healthy 30-year-old grandson, then I think most doctors would take the guidance with a pinch of salt and allow them to say goodbye in person."

The guidance also outlines how NHS hospitals should allow junior staff to take on more advanced roles to prevent the system becoming overwhelmed.

Clinicians with "non-essential managerial roles" should be redeployed to the front line, it says, while "staff groups with critical care expertise may need to move to supervisory roles rather than bedside clinical care".

"Any staff member can assist with moving equipment, restocking units, resupplying bed areas and completing administrative tasks," it adds.

The document also advises in detail how newly-trained staff should ventilate coronavirus patients if they are struggling to breathe.

"Manual ventilation, or 'hand-bagging' is not advised," it says.

Meanwhile hospital staff are told to "support each other" through the crisis, and not allow leaders to make critical decisions alone.

"Leadership in a crisis is stressful and demanding. The clinical director alone cannot do everything," it says.

"Ensure strong support of physical and mental wellbeing, focusing on emotional support, nutrition, hydration and sleep."

Simon Stevens, Chief Executive of the NHS, confirmed yesterday that the vast majority of visitors would be banned from hospitals in England in a bid to curb the spread of the coronavirus, although there would be exceptions in some cases.

The announcement came after doctors were warned last week that they may have to perform tasks for which they are not properly trained to cope with the "abnormal emergency" of coronavirus.

Prof Chris Whitty, the Chief Medical Officer for England, told medics that a flood of patients with Covid-19 could force them "to depart, possibly significantly, from established procedures in order to care for patients in the highly challenging but time-bound circumstances of the peak of an epidemic".

In an open letter, which he shared in a tweet, Prof Whitty called on NHS staff to "stick to the basic principles of being a good doctor", applying a "rational approach to varying practice in an emergency".