The East of England ambulance service has declared a critical incident as NHS services around the country face “unprecedented” pressure.

North East Ambulance Service, South East Coast Ambulance Service and the East of England Ambulance Service have all moved to the status as staff work to respond to calls.

The latter works in Essex as well as Bedfordshire, Hertfordshire, Norfolk, Suffolk and Cambridgeshire.

The East of England Ambulance Service, declaring critical incident status in a statement on Monday, said it was “currently under huge pressure as a consequence of 999 call volumes and hospital handover delays”.

“Declaring a critical incident means we can ensure our resources are focused on patients with the greatest need, as well as allow us to access wider support from our health and care partners,” the trust said.

North East Ambulance Service said it declared a critical incident on Monday afternoon as a result of “significant delays for more than 200 patients waiting for an ambulance, together with a reduction in ambulance crew availability to respond because of delays in handing over patients at the region’s hospitals”.

Stephen Segasby, chief operating officer at the service, said: “Our service is under unprecedented pressure.

“Declaring a critical incident means we can focus our resources on those patients most in need and communicates the pressures we are under to our health system partners who can provide support.

“We are asking the public to call us only in a life-threatening emergency.”

Mr Segasby urged other patients to speak to their GP or pharmacist or use the NHS 111 website.

“Our staff and volunteers continue to work extremely hard to respond to calls and incidents,” he said.

“I would like to take this opportunity to thank them for their hard work and commitment at this challenging time.”

The ambulance service said declaring a critical incident allows it to instigate several additional measures to protect patient safety.

This includes seeking mutual aid, cancelling all training to allow for the redeployment of all clinical staff, no longer taking bookings for urgent non-emergency transportation and increasing third-party provider provision.

South East Coast Ambulance Service said it decided to declare a critical incident on Monday “following a period of more than a week of sustained pressure across our 999 and 111 services, significantly impacting on our ability to respond to patients”.

The moves to declare critical incidents come as fears grow over the impact of an ambulance strike on Wednesday, when thousands of paramedics, technicians, control room workers and other staff walk out