A leaky roof caused by heavy rainfall has forced the closure of a ward at Stevenage's Lister Hospital, triggering a level of alert that indicates the hospital is "unable to deliver comprehensive care" and "there is increased potential for patient care and safety to be compromised".

Mel Gunstone, deputy chief nurse at the East and North Hertfordshire NHS Trust, which runs Lister, said: “Last night (Tuesday) we closed a ward at Lister Hospital due to leaks in the roof, caused by heavy rainfall.

“All patients on the ward have been moved to ensure they continue to receive high-quality care in a safe environment, and relatives notified.

“Our estates team and roofers are working hard to fix the leaks, and we hope to be able to move patients back onto the ward later today.”

The ward affected is 11A (north and south).

The NHS Trust declared a business continuity incident yesterday afternoon and is at OPEL4 - operational pressures escalation level 4 - which is the highest level. A spokesman for the NHS Trust said: "It means we are experiencing severe operational challenges despite implementation of agreed action, with little or no likelihood of improvement within the next four hours."

According to NHS England's framework, OPEL4 means "pressure in the local health and social care system continues to escalate, leaving organisations unable to deliver comprehensive care. There is increased potential for patient care and safety to be compromised."

The NHS Trust spokesman said: "Unless you have a life or limb-threatening emergency, please contact NHS 111 first or attend the New QEII Hospital Urgent Treatment Centre in Welwyn Garden City between 8am and 10pm for minor injuries and illnesses."