Hundreds of consultants working for the Royal Free NHS Foundation Trust have written to the health secretary, Jeremy Hunt, backing junior doctors over possible industrial action.

In a letter signed by 505 of the trust’s 800 consultants, senior doctors called for Mr Hunt to “urgently reconsider his stance and facilitate meaningful negotiations” in a row over changes to junior doctors’ contracts.

They described their junior colleagues as “an integral part of the NHS [who] already work 24/7 rotas to deliver frontline care”.

Their comments came a day after the British Medical Association (BMA) announced junior doctors would vote on striking over three dates in December.

The letter, published on Friday in the Guardian, read: “An empowered, rested, happy and appropriately remunerated workforce across all cadres of medical, nursing and allied health professional staff is essential to sustain high clinical standards in the face of increasingly complex healthcare delivery challenges.

“We regret, yet clearly understand, that public protest and possible industrial action by doctors has become necessary to safeguard these basic requirements.”

All signatories work at the trust-run Royal Free, Chase Farm and Barnet hospitals and include leading professors.

The BMA ballot will end this Wednesday. If there is a Yes vote, junior doctors will only provide emergency care for 24 hours from 8am on December 1, followed by full walkouts from 8am to 5pm on December 8 and 16. It would likely mean planned operations and clinics cancelled during this time.

The new contract, to be implemented next year, revolves around what the government says is a commitment to improving NHS care seven days a week.

Junior doctors – some 20,000 of whom marched in London last month – says the contract removes vital safeguards which discourage their employers making them work dangerously long hours. They also say it will extend working hours for which they receive basic rates of pay, including on Saturdays.

Mr Hunt last week described the proposed strike action as “extreme”. He said maximum working hours per week would fall under the new deal and insisted junior doctors would not lose out financially.

The BMA and Mr Hunt have blamed each other for the breakdown in negotiations.

BMA council chair Mark Porter said of the “extraordinary” strike announcement: “We are releasing this information at this early stage because we want to give as much notice as possible.

“It sounds like an oxymoron when talking about industrial action, but we genuinely want to minimise any disruption to other NHS staff and, above all, to patients.

“Our dispute is with the Government and our ballot for industrial action is a last resort in the face of their continued intransigence.”

The BMA said it has told the government it wants to work with it to agree a new contract, but it needs a number of concrete assurances.

These include withdrawal of the threat to impose the new contract, proper recognition of unsocial hours as premium time, no disadvantage for those working unsocial hours compared with the current system, and no disadvantage for those working less than full- time and taking parental leave compared with the current system.

After the proposed strikes were announced, Mr Hunt said: “Threatening extreme action is totally unwarranted and will harm vulnerable patients.

“Refusing to talk to a Government that wants to improve weekend care for patients and reduce doctors’ hours can only damage the NHS.

“Rather than striking, the BMA should return to the negotiations they walked away from a year ago and put their patients first.”