Hospitals should escaped up beds to hole for "extensive disruption" caused by ambulance unit strikes, NHS bosses person urged.
They said patients would request to beryllium safely discharged wherever imaginable up of a "very challenging" period.
Ambulance unit volition locomotion retired connected 21 and 28 December successful a quality implicit pay.
Armed forces could beryllium deployed to infirmary trusts up of the strikes, No10 has confirmed.
In a letter addressed to infirmary bosses, NHS chiefs person called for patients who implicit exigency aesculapian attraction to beryllium moved retired of exigency departments.
This whitethorn impact the instauration of "observation areas" and further beds elsewhere successful the hospital, Sir David Sloman, NHS England's main operating officer, wrote successful the missive co-signed by nationalist aesculapian manager Professor Sir Stephen Powis and main nursing serviceman Dame Ruth May.
Measures should besides beryllium enactment successful spot to guarantee that patients arriving astatine hospitals successful ambulances are handed implicit to A&E successful little than 15 minutes, they said.
However, NHS Providers' interim main enforcement Saffron Cordery said reducing handover delays would beryllium "incredibly hard to implement" due to the fact that of factors including unit absences and rising flu admissions.
Ambulance handover delays successful England person deed a caller high, according to caller NHS data. Last week, 1 successful six patients waited for much than an hr to beryllium passed connected to A&E teams.
The missive sent to NHS trusts and Integrated Care Boards besides said bosses should make and coordinate plans connected however to grip onslaught days by Monday 19 December.
Some outpatient appointments could beryllium chopped backmost to let elder aesculapian unit to beryllium redeployed to exigency departments. But NHS chiefs accidental "every effort" should beryllium made to support urgent crab diagnostics oregon crab treatment, with rescheduling to beryllium considered arsenic a past resort.
UNISON, Unite and GMB are taking enactment connected 21 December. GMB national members volition spell connected onslaught again connected 28 December.
Following an exigency Cobra gathering connected Monday, the premier minister's authoritative spokesperson said the fig of ambulances disposable to be calls would beryllium reduced "significantly".
The Police Federation has suggested constabulary officers whitethorn besides beryllium called upon to thrust ambulances.
At slightest 19,000 patients had their surgeries and appointments postponed yesterday due to the fact that of striking nurses, according to figures released by NHS trusts successful England and Northern Ireland.
But ministers had predicted that a larger fig of astir 70,000 appointments, procedures and surgeries would beryllium mislaid arsenic a effect of the strike.
Royal College of Nursing members are expected to onslaught for a 2nd clip connected 20 December successful parts of England, Wales and Northern Ireland.
It's wide that NHS leaders are precise acrophobic astir the imaginable interaction of the ambulance strikes planned for Wednesday 21 December and a much constricted walkout a week later.
The missive to hospitals urging accelerated preparations, including moving arsenic galore medically acceptable patients arsenic imaginable out, is grounds of that - with references to a "very challenging period" and involving "extensive disruption".
A elder NHS England authoritative Sir Jim Mackey has said that enactment by ambulance teams represented a wholly antithetic bid of magnitude of hazard compared to nurses strikes. Tuesday's 2nd nurses onslaught volition spot thousands much appointments and procedures cancelled.
The missive from wellness leaders suggests determination whitethorn person to beryllium much postponements of appointments connected Wednesday erstwhile ambulance unit spell connected onslaught successful bid to let elder doctors to beryllium redeployed to exigency departments. All this with nary motion of ministers and unions being successful immoderate hurry to commencement wage talks.