North West Ambulance Service (NWAS) 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.
A spokesman said there is nothing to indicate that the surge in calls is linked to Covid-19.
“Due to a high level of calls into our service, the trust has declared a major incident,” a statement said.
“This is being managed in accordance with out usual protocols and we are urging the public to only call us if their condition is life-threatening or potentially life-threatening.
“Traditionally, Mondays are often a very busy day for us and we are unsure as to why we are seeing a surge today.
“There is currently nothing to indicate this increase in calls is in relation to Covid-19.
“We are putting in place additional support throughout the North West and will be closely monitoring this situation throughout the evening.
“There are patients who are facing delays and we are very sorry that we are unable to respond as quickly as we would like.
“Please help us by not calling us to check where the ambulance is as we need those lines to be free for those in a life-threatening condition. However, if you feel you no longer need an ambulance, please let us know.”
NWAS said there has been a “high level of activity” in the region, especially the Greater Manchester area.
But the spokesman said the service has seen a reduction in calls since the major incident was declared.
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.”