The North West Ambulance Service has declared a major incident due to a high level of calls.
The ambulance service said it was “exceptionally busy” on Monday evening and warned patients to expect delays.
“We’ve declared a major incident due to the high level of calls,” a statement said.
“If your call is not life-threatening, you may be asked to seek an alternative source of care or make your way to hospital.”
The North West Ambulance Service (NWAS) said there has been a “high level of activity” in the region, especially the Greater Manchester area.
A statement on Facebook said: “You can help us reach the patients that urgently need our help by not calling 999 unless the condition is life-threatening or potentially life-threatening, not calling us to find out where your ambulance is or calling to cancel any ambulance that you no longer require or feel is necessary.
“We are trying our best to reach patients as soon as we possibly can and apologise for any delays in our response. Please bear with us.”
Staff had agreed to cancel breaks for two hours between 5pm and 7pm, according to the NWAS branch of the trade union Unison.
NWAS Unison said on Twitter: “Please help our crews by only calling if you really need us.
“They are being run ragged at the moment and they will get to you as soon as they can. Please consider using 111 first. Thank you.”