After facing increased disruption at security gates over the weekend, Manchester airport apologised to customers and admitted passengers’ experiences "fell below the standard we aim to provide".
"Our whole industry is facing staff shortages and recruitment challenges at present, after the most damaging two years in its history," an airport spokesperson said.
"The removal of all travel restrictions after two years, coupled with the start of the summer travel season, has seen a rapid increase in passenger numbers, which is putting an enormous strain on our operation."
The airport said it was recruiting extra staff to meet the increase in demand, but it faced delays due to the vetting and training processes involved.
"That is why we have been advising travellers that there may be, at times, longer queues than normal," the spokesperson added. "Whenever this is the case, we do all we can to redeploy resources and prioritise passengers within queues as best we can.
"We are also aware that partners working on our site, such as baggage handling agents, are facing similar challenges. We will continue to support them in any way we can to deliver the best possible experience for customers during this challenging time."
Meanwhile, Stansted warned passengers of "some disruption" in the coming weeks in its departure lounge as it undergoes a "major" £12.5 million refurbishment.
An estimated 1.3 million passengers will travel through the London airport over the Easter holidays, making it the "busiest period for travel" since before the pandemic began.
Stansted has encouraged passengers to arrive in good time for their flights and to familiarise themselves with all the usual security requirements before arriving at the airport.
Steve Griffiths, Stansted’s managing director, reassured people the airport is "working hard to get back to where we need to be".
"While queues may be longer than people are used to at times, customers can definitely help us by arriving in good time," he added.
"Over the next few weeks, passengers may experience some disruption in the departure lounge, so please be patient with us as we carry out this work.
"We are all really excited to welcome more and more passengers back to London Stansted and will be working hard to ensure they have the best possible experience while at the airport."
Elsewhere, easyJet was forced to cancel more than 200 flights over the weekend due to high levels of staff absence owing to Covid-19.
Gatwick also reportedly told the BBC it had a busy weekend as the Easter holidays kicked off.
