DUBAI (Reuters) - Emirates is facing a cabin crew shortage and is struggling to fully staff some flights after a spate of resignations and other workforce constraints, several employees told Reuters.

Emirates Airlines flight attendants come through the International Arrivals gate from Dubai at Dallas/Fort Worth International Airport in Texas, U.S., June 29, 2017. REUTERS/Laura Buckman

Seven Emirates employees said the airline was operating flights with fewer cabin crew than usual and increasingly reassigning flight attendants to other routes at the last minute to enable them to operate.

Emirates’ fleet of Airbus A380 and Boeing 777-300 jets requires more cabin crew per flight than smaller aircraft and to meet the requirements of long-haul routes.

The Dubai-based airline denied it had a cabin crew shortage and said it had slowed down recruitment across the company last year, including for crew, but had recently started actively recruiting crew again.

“Our recruitment activity, as well as our adjustment of the crew complement on some aircraft types, is all part of any normal business review,” the airline said in a statement to Reuters.

Four employees told Reuters that a series of resignations among cabin crew and a spike in the number of crew calling in sick had put pressure on the airline.

The cabin crew staffing issue follows on from a pilot shortage which Emirates said in April meant it would have to cut back on the frequency of some routes this summer.

Major airlines are having to adapt to a more competitive marketplace and the impact this has on staffing. Ryanair RYA.I, Europe’s biggest budget airline, was forced last year to recognize unions to avoid a Christmas strike after a shortage of standby pilots forced it to cancel flights.

Emirates, which employs about 25,000 cabin crew staff from around the world, has seen growth affected over the last few years by lower oil prices, a major driver of wealth in the Gulf region, and volatile demand.

The employees said there was no suggestion that the airline was operating flights with fewer cabin crew or pilots than required by regulations or that employees were exceeding working hours set by regulators.

The airline is holding recruitment open days for new crew in at least 12 countries this month, including the United States, United Kingdom and France, according to one of its websites.

According to an internal Emirates email dated April 8, seen by Reuters, a “significant increase in on-the-day sicknesses reports” due to a change in the way sick leave is reported was impacting “crew rostering and operations”.

Some employees said the carrier has tried to mitigate staff shortages by asking pilots and cabin crew to work longer hours each month.

The airline is assigning two fewer cabin crew on some flights from May to “ensure consistency across our aircraft configuration”, according to another internal email dated April 12 and seen by Reuters.

In a bid to improve working conditions and benefits following complaints from cabin crew in February, Emirates has started providing them with full medical coverage and is reviewing calls for pay increases, according to employees.

Emirates is scheduled to report its annual results on Wednesday.