Several additional hours were spent in ambulances caused by delays at the Royal Surrey County Hospital last week, new figures show.
Across England, one in six patients waited more than an hour, while one in three were left waiting more than 30 minutes – both record highs.
The figures cover the week before nurses conduct their first nationwide strike in England, Wales and Northern Ireland this week – the largest action in NHS history, with the organisation saying it is doing all it can to minimise disruption.
Membership organisation NHS Providers said NHS trust leaders are concerned strike action and recent cold weather will add to the pressure on already stretched ambulance services.
NHS England figures show three patients waited in an ambulance for at least one hour when they arrived at Royal Surrey County Hospital NHS Foundation Trust A&E in the week to Sunday (December 11) – up from one the week before. A further 33 patients were forced to wait between 30 minutes and one hour, meaning 13% of the 277 total ambulance arrivals were delayed by half an hour or more, and at least seven hours were lost.
NHS targets state trusts should complete 95% of all ambulance handovers in 30 minutes, with all conducted in less than one hour.
Around 25,000 handover delays of half an hour or longer were recorded across all hospital trusts last week, according to NHS England.
It meant a record 34% of all arrivals by ambulance were postponed by more than 30 minutes – up from 31% the previous week.
Meanwhile, 12,500 patients (17%) had to wait more than an hour to be handed over, also a record.
A handover delay does not always mean a patient has waited in the ambulance as they could have been moved into an A&E department but the handover was not completed.
Pat Cullen, general secretary and chief executive of the Royal College of Nursing, said nurses are going on strike "for fairness, for the future of our NHS, and to stand up for fair pay and for patient safety".
Saffron Cordery, interim chief executive at NHS Providers, said: "Ambulance handover delays have also increased, with over a third being delayed by 30 minutes or more.
"Trust leaders are concerned that unfolding strike action and the extremely cold weather will add even more pressure to overstretched services.
"The Chancellor's commitment to publishing a long-term workforce plan in 2023 is welcome, but this must be backed by appropriate funding for implementation."