Strikes could see patients “stranded” in hospital over Christmas, despite being ready to go home, leading health and patient organisations have warned.

Experts warned that the timing of the strikes mean it will be “extremely difficult to ensure safe and effective care” during the walk outs, which begin at 7am on Wednesday.

Age UK, NHS Confederation, Healthwatch England, National Voices and The Patients Association have written to the British Medical Association (BMA) and the Government expressing concerns over the strikes.

They wrote: “There were 13,000 patients – many older people – waiting to be discharged in the first week of December. Strike action in the run up to Christmas could see these numbers increase, leaving patients stranded in hospital over the holiday period despite being medically fit for discharge.”

They added: “Our concern is that, despite the best efforts of hard-working NHS staff, it will be extremely difficult to ensure safe and effective care during this period for all patients that need it.”

They said that the Government and BMA must work to find a solution to the strikes, saying the current position is “clearly unsustainable”.

Meanwhile they said that no national exemptions for the walk out had been agreed.

“The timing, duration and fact that – as yet – no national derogations have been agreed is cause for alarm,” they wrote.

“As a minimum, we are calling on all parties to take a step back and agree national derogations in our most vital ‘life and limb’ services so they can continue to operate in full over the period.”

Caroline Abrahams, charity director at Age UK, said: “We have been hearing from distressed older people about how their outpatient appointments and operations scheduled for strike days have had to be postponed, sometimes for months, and for some unlucky people on more than one occasion.

“Make no mistake, these postponements have had real consequences for them by slowing down the diagnosis of serious illnesses, as well as delaying surgery to deal with cataracts and degraded hip and knee joints that seriously interfere with daily life and often cause them ongoing pain.”

She continued: “With the best will in the world, it is hard to guarantee patient safety and wellbeing if you are operating a hospital with a skeleton clinical staff, one that will already be being depleted by staff sickness and annual leave.”

Matthew Taylor, chief executive of the NHS Confederation, added: “Any strike is highly disruptive but worse still there is no agreement on national derogations. Without this agreement for doctors to provide urgent and critical ‘life and limb’ cover, the risk to patient safety, and strain on other staff, is further heightened.”

Responding, Professor Phil Banfield, chair of BMA council, said: “We are as disappointed as our patients are at being in this position again.

“During all strike action by junior doctors, ‘life and limb’ care has been preserved and indeed enhanced in many places by being provided by the most senior and experienced doctors in the NHS – consultants and specialists.

“This has been the case throughout the junior doctor action, which precludes the need for national derogations. As we have with previous rounds of industrial action, we will carefully consider any requests we receive for a derogation and give each one due regard, based on its merits, but at this stage we have not received any requests for derogations from NHS England.

“As the letter states, there were 13,000 patients awaiting discharge in the first week of December; giving trusts plenty of time with proper planning, resources and additional staffing, to discharge them prior to strike action this week.

“We have given Trusts notice of the strike action to enable them to put plans in place to provide the level of cover they believe is needed at a local level, but we would emphasise that it is incumbent upon the Health Secretary and Government to provide the junior doctors with a credible offer to prevent the strikes going ahead and thus prevent further disruption to patient care.”

The NHS has said emergency and urgent care will be prioritised during the strikes and “almost all” routine care will be affected.

Junior doctors in England are to take to picket lines from 7am on December 20 to 7am on December 23 in a major escalation in the bitter dispute over pay.

The second planned strike by BMA junior doctors will be the longest in NHS history, lasting six full days from January 3.

The industrial action comes at one of the busiest times of the year for the NHS as it grapples with increased pressure from winter viruses including flu, Covid-19 and norovirus.

The NHS said that in the coming three weeks only two weekdays in the NHS are unaffected by holidays or industrial action.