The health secretary’s legal challenge against the Royal College of Nursing’s forthcoming strike is a “blatant threat”, the union’s leader has said. Steve Barclay’s decision to refer to the courts, revealed on Friday, is the latest twist in the long-running saga over pay between nurses and the government. Nurses are gearing up to strike from 8pm on 30 April until 8pm on 2 May, but the legality of the final day is currently in dispute – as it could fall out of the union’s six-month mandate. The RCN general secretary, Pat Cullen, blasted the health secretary’s decision as “cruel” and “unacceptable” on Saturday morning. But Barclay said he had “no choice” but to take action after NHS Employers wrote to him asking to check if the 2 May strike was unlawful. He said the strikes would put patient safety and the professional registration of nurses “at risk”. Speaking to BBC Radio 4’s Today programme, Cullen said: “We have managed six months of industrial action and we have done that in the most safe and effective way. “We will certainly not put our members at risk, we certainly won’t put our patients at risk. “But for Steve Barclay to come out yesterday and say that he was doing this to protect the registration of nurses, well you can see how nurses interpreted that. “That was a blatant threat to our nursing staff to say: ‘If you don’t stop this and accept my pay offer then your registration perhaps may be at risk.’ “We will never put our nurses at risk and we certainly won’t put their registration at risk.” Barclay had 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 Mayto 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. “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.” Cullen urged ministers to “calm this down” and resume negotiations. She said the union had been planning with NHS England and other service leaders for the potential industrial action next month, including ensuring there were protocols for escalation to ensure patient safety was not put at risk. However, she went on: “If the court finds against us, then we will absolutely work within the parameters of the law. We will never do anything illegal. Nurses don’t work like that, and I’m a nurse myself. “But if nursing is defeated then it is, in my mind, and in our nurses’ minds, an even darker day for this government.”