Brexit poses a “grave danger” to the NHS and is distracting attention away from the urgent issues facing the service in what could be the “toughest winter yet”, senior doctors have warned.

The British Medical Association is marking the 100 days until Brexit milestone by repeating its call for a second referendum.

The doctors’ union is also warning that with the country is facing what could be the “toughest winter yet”, the government and NHS need to “urgently” outline plans to tackle seasonal pressures.

Its call follows the decision to delay publishing the NHS long-term plan which will set out how the service will invest the £20.5 billion a year by 2023-4 promised in the budget.

The BMA said Brexit will affect all areas of the NHS including workforce, access to medicines and radioisotopes, and health security.

A survey by the union found more than a third of EU doctors are considering leaving the UK.

The BMA said that with EU doctors making up 10% of the medical workforce, this could pose a “real risk” to patient safety.

The union also warned Brexit could make it harder to access new medicines or vital radioisotopes used for cancer treatment and diagnosis of disease.

It said only by remaining a member of the European Union can Britain continue to have access to the same benefits.

BMA council chair Dr Chaand Nagpaul said the only certainty about Brexit was how “disastrous” it will be for the health service.

He added: “The only thing that is certain, is how disastrous leaving the EU will be for the NHS, its workforce, its patients and the health of the country as a whole – and that no type of Brexit can ever offer the same benefits we currently have.

“Given the very real health threats that Brexit brings, the British public must be given a final say on any deal in a second referendum.”

Dr Nagpaul said the “political chaos” at Westminster means that the country’s most urgent healthcare needs were not being addressed despite winter rapidly approaching.

He added: “We were assured that the Government was going to lay out its long-term plan for the NHS before Christmas, but the Brexit stalemate means this has now been delayed until at least the new year.

“We are on the brink of what we know will be weeks of overcrowding in hospitals, patients waiting many hours on trolleys and staff pushed to the limit of their physical and emotional wellbeing – the annual winter crisis.

“The shambles surrounding Brexit will mean that the NHS, patients and staff will suffer this winter as the Government is diverted from addressing the very real crisis on their doorstep.”