Members of the Royal College of Nursing (RCN) working in the NHS in England are preparing to take industrial action for 48 hours over the May bank holiday.

They are set to walk out from 8pm, or the start of a night shift on 30 April, until 8pm or the start of the night shift on 2 May.

The action will see nurses in emergency departments, intensive care and cancer wards down tools for the first time.

NHS bosses wrote to Health Secretary Steve Barclay asking him to check the legality of the strike action, before the mandate expires in May.

In a statement, Mr Barclay said: "Following a request from NHS Employers, I have regretfully provided notice of my intent to pursue legal action to ask the courts to declare the Royal College of Nursing's upcoming strike action planned for 30 April to 2 May to be unlawful.

"The government firmly believes in the right to strike, but it is vital that any industrial action is lawful and I have no choice but to take action.

"Strike action with no national exemptions agreed, including for emergency and cancer care, will also put patient safety at risk."

Mr Barclay warned nurses that taking part in the action could put their careers in jeopardy.

"This legal action also seeks to protect nurses who could otherwise be asked to take part in unlawful activity that could, in turn, put their professional registration at risk and would breach the requirements set out in the nursing code of conduct," he said.

But RCN general secretary and chief executive, Pat Cullen, branded the move "nakedly political".

"Nurses will not be gagged in this way by a bullying government," a statement said.

"We are clear that court arguments should only relate to 2 May and not 30 April and 1 May.

"The government is now desperate to silence nurses rather than address this properly. We want to be in the negotiating room, not the courtroom."

A statement from the RCN added: "Bullying nurses and dragging us through the highest courts would not be a good look for the government.

"It would show utter contempt for nursing staff."

Mr Barclay revealed his intent to launch legal action after nurses in England represented by the RCN rejected an offer of a 5% pay rise last week.

The offer was rejected, despite a recommendation by union leaders to accept the deal.

An NHS leader warned that an escalation of action would "endanger patient safety".