Hospital chiefs have apologised after mounting pressures led to reports by the public of a seven hour waiting time in Royal Preston Hospital's A and E department.
One man claimed 10 ambulances were backed up outside the busy department during the crisis on Monday morning.
Karen Partington, chief executive at Lancashire Teaching Hospitals NHS Foundation Trust said: " “Winter is an exceptionally busy period for hospitals around the country.
"We are looking after more acutely unwell patients than usual, and despite our best efforts there are inevitably delays when we are exceptionally busy, which we know is not ideal.
“Our staff are working with great commitment and compassion to look after the continuingly increasing number of patients who need hospital care.
"We apologise to every patient who has experienced delays.
"We trust that everyone understands that we must prioritise those who need emergency treatment.”
A hospital spokesman did not confirm the alleged seven hour waiting time, adding: " A&E times are forever changing, depending on what cases staff are dealing with, and what people are coming in with."
A spokesperson for North West Ambulance Service (NWAS), said: “Yesterday evening leading into the early hours of this morning was a particular busy period for us in South Lancashire with a number of patients being transported to Royal Preston Hospital.
“We continue to work very closely with our hospital colleagues to put in place a number of initiatives to help free up our ambulance clinicians, getting them back out into the community as quickly as possible so they’re able to respond to patients in emergency situations.
“By working with collaboratively with key hospitals such as Royal Preston Hospital, last winter we were able to significantly reduce hospital handover times and the project has been expanded for this year.
“As always the public can assist us, in what is our busiest time of year, by only calling 999 in emergencies and considering other healthcare providers such as GPs and pharmacies if their condition is not serious. NHS 111 Online is available for urgent medical advice if it’s not an emergency.”
It comes just three months after the future of Chorley A&E was debated by councillors , with concersn raised about the pressure this might cause for the Royal Preston Hospital.
And in the summer a CQC inspection said the hospital "needs improvement" as patients waiting for emergency treatment had to wait longer than national standards.
However, the trust's website says it as made " huge improvements" to the emergency department at Preston, with a £1.9m funding boost to improve facilities and increase capacity.
Improvements include a new rapid assessment triage space to enable ambulances to handover patients without delay, extra cubicles to treat patients with serious conditions, upgraded high acuity cubicles, a new space for frail or elderly patients, extra surgical assessment capacity, a mobile x-ray, and IT systems to improve bed management.