Hospitals are under "extreme pressure" with waiting times in A&E reaching in Bolton “up to 11 hours."

The difficulty comes as a number of hospitals have called on junior doctors to return to work due to patient safety concerns.

The strike is the longest walkout in the history of the NHS.

Yesterday was the first day of the six day walkout by junior doctors.

Elsewhere in the UK two hospitals have declared critical incidents.

Some have issues derogation requests calling on doctors to return to work.

The British Medical Association said a number of these were sent in advance of the strike and hospitals had not shown what steps they had taken to mitigate the need for junior doctors to work.

It is understood 20 of these have been made but 19 have been rejected and one is under consideration by the union.

Amidst this Bolton NHS Foundation Trust said it was facing "extreme pressure" and waiting times in A&E of "up to 11 hours" , that fell to four hours plus on Thursday morning, with bosses saying that "our emergency department is currently experiencing extremely high levels of activity".

Earlier this week the hospital said it was doing all it could to minimise disruption.

Critical incidents were declared at Queen Alexandra Hospital in Portsmouth and also at NHS Nottingham and Nottinghamshire Integrated Care Board.

Health officials in Wigan have said emergency services were "very busy" and doctors were seeing 

 “a lot of minor illnesses that could have been treated elsewhere such as a GP surgery or pharmacy”.

In a letter to NHS boss Amanda Pritchard, BMA chairman of council Professor Philip Banfield said: “It is, therefore, astonishing that during this current round of industrial action, NHS England and some Trusts have refused to evidence any efforts to source alternative staffing or demonstrate rearrangements or cancellation of less urgent work.”

He added: “We are increasingly drawing the conclusion that NHS England’s change in attitude towards the process is not due to concerns around patient safety but due to political pressure to maintain a higher level of service, undermine our strike action and push the BMA into refusing an increasing number of requests; requests, we believe, would not have been put to us during previous rounds of strike action.

“The change in approach also appears to be politicisation and weaponisation of a safety critical process to justify the minimum service level regulations.”

An NHS spokesperson said: “The NHS has a robust process in place for seeking derogations from the BMA to prioritise the safety of our patients and this has involved providing strong evidence where the most challenged systems need support.”