Trust leaders have raised fresh concerns over patient safety ahead of next week's four-day strike by junior doctors.

They have told NHS Providers, which has every NHS hospital, mental health, community and ambulance service in England in membership, that the walkout presents a range of challenges over and above the disruption seen from the industrial action in recent months.

Once again trusts are working to mitigate the impact of the strike but say its timing – coming off the back of the Easter bank holiday weekend, when many colleagues are also on annual leave – and duration of four full days are making it harder to assure patient safety.

During the strike, the NHS will focus resources on emergency treatment, critical care, maternity, neonatal care and trauma. But even in these areas, there are real concerns of a raised risk to safety.

During extensive soundings, trust leaders told NHS Providers about the additional challenges they face.

One hospital trust chief executive said: "This is less about what planned routine work gets pulled down, and everything about maintenance of safety in emergency departments, acute medicine and surgery". He added: "Concerned doesn't begin to describe it."

Another said: "I am not confident this time that we can maintain patient safety as we will not be able to provide the cover."

A third said: "Many of the consultants who stepped up to do nights last time are not available or are more reluctant this time", while another observed that: "Those with families almost certainly won't as [they] can't rearrange out of school holidays."

While most attention during recent strikes has focused on hospitals, there was also deep concern among mental health and community trust leaders: "Don't forget mental health – our services always run very hot. Asking consultants to cover for doctors in training raises the risk through the acute mental health pathway since other essential work won't get done."

The chief executive of NHS Providers, Sir Julian Hartley, said:

"It's clear from our extensive dialogue with trust leaders that we are in uncharted territory.

"Yet again we are seeing colleagues pull out all the stops to minimise disruption and ensure patient safety.

"But the challenges here are unprecedented.

"It's particularly important during the strike that in the event of an emergency the public continue to turn to the NHS. No effort will be spared to provide the care they need.

"But for less urgent cases, people should look first to 111 online if they can, to access appropriate treatment and advice.

"Even now it's not too late for the two sides in this dispute, the government and the unions, to recognise the gravity of the situation and step back from the brink.

"We need a solution to prevent further strikes, and we need it now."