Jeremy Hunt’s legal power to impose a controversial new contract on junior doctors has been put into question following what appears to be U-turn from the Health Secretary.

A letter seen by the Guardian states the Health Secretary is “introducing” the contract, rather than unilaterally “imposing” it upon junior doctors.

Mr Hunt had previously said he may opt for the “nuclear option” to "impose" the new proposals if no deal was reached over the changes to hospital doctors’ working contracts.

The revelation comes ahead of a High Court Challenge on Monday, which initiates a judicial review of the lawfulness of the Health Secretary’s right to impose the contract.

Junior doctors have already staged four strikes over the new plans and a further all-out strike is set to take place on 26 and 27 April. Unlike during previous strikes, emergency care will also be withdrawn.

In the newly revealed letter, sent last Friday by the Government Legal Department to solicitors acting on behalf on a group of junior doctors opposing the contracts, Government solicitors state Mr Hunt will “proceed with the introduction of a new contract” and that he is legally entitled to do so under the NHS Act 2006.

In pictures: Junior doctors protests in UK Show all 10 1 /10 In pictures: Junior doctors protests in UK In pictures: Junior doctors protests in UK 20,000 Junior Doctors marched through central London in protest at the new contract changes the government is trying to impose which they say will be unfair and unsafe In pictures: Junior doctors protests in UK Junior doctors protest in London In pictures: Junior doctors protests in UK 4 year old Cassius takes part in a demonstration in Westminster, in support of junior doctors over changes to NHS contracts, London In pictures: Junior doctors protests in UK Protest over proposed changes to junior doctors' contracts, Leeds In pictures: Junior doctors protests in UK Junior doctors and NHS staff protesting against the health service cuts and the proposed contract changes offered by the government outside Parliament In pictures: Junior doctors protests in UK Junior doctors and NHS staff protesting against the health service cuts and the proposed contract changes offered by the government outside Parliament In pictures: Junior doctors protests in UK Over 5000 junior doctors rallied in Waterloo place, before marching through Whitehall and onto Parliament Square, in opposition to Jeremy Hunt's new working conditions for doctors In pictures: Junior doctors protests in UK Demonstrators listen to speeches in Waterloo Place during the 'Let's Save the NHS' rally and protest march by junior doctors In pictures: Junior doctors protests in UK Junior doctors marched in London to highlight their plight In pictures: Junior doctors protests in UK A protester at a demonstration in support of junior doctors in London

At no point does the five-page document mention an “imposition”.

Norman Lamb, a Liberal Democrat health minister, said the new wording is “quite a dramatic change”.

“If he’s changed the language from ‘imposing’ to ‘introducing’, it may be that there’s no way the government can continue to try to get this contract implemented,” he said.

Heidi Alexander, the shadow health secretary, said: “Government lawyers appear to be trying to rewrite history in an attempt to get Jeremy Hunt out of what could be a very significant legal problem.”

In response, Mr Hunt has said on Twitter that the government has done what it is “entitled to” following a "disappointing" and “needless refusal” to negotiate by the British Medical Association (BMA).

Junior Doctors Contract

A Department of Health spokesperson said there had been no change in the Health Secretary’s language in relation to the contracts.

Junior doctors are objecting to a new contract under which they would be required to work more weekends and lose extra pay on Saturday in exchange for a basic pay rise of 13.5 per cent.

Jeremy Hunt has said the government has done what it is 'entitled to' (Dan Kitwood/Getty Images)

The Government says the contract will help implement the Conservatives’ manifesto pledge of improving care at weekends, dubbed a “seven-day NHS”, while junior doctors say a new contract will put patient safety at risk by incentivising unsafe staff rostering.

The dispute has become increasingly bitter and has seen junior doctors go out on strike for the first time in 40 years.