Aer Lingus is to lay off 100 more staff after it saw a first quarter operating loss deepen by €9.4 million to €45.5 million.

The higher loss was largely due to wet-lease start-up costs for supplying aircraft to Virgin Atlantic’s Little Red UK domestic arm, planned changes to the long-haul fleet and slightly weaker trading on UK routes.

The Irish carrier expects its 2013 operating profit, before exceptional items, to be broadly in line with last year.

Long-haul yield and load factor performance was particularly strong in the first three months of the year, increasing by 5.6% and 3.4% respectively.

Chief executive Christoph Mueller said: ”In line with the ongoing requirement to streamline our organisation structure and identify cost saving initiatives, we are launching a voluntary severance programme, with a goal of reducing headcount by approximately 100 staff by year end.”

The fist quarter performance “highlights the need to continue to review our cost base to protect profitability for the rest of 2013 and beyond,” he said.

“We have delivered revenue growth of 3.3% in the first quarter and are particularly pleased with the performance of our long-haul business which is up 14.4% on the prior year,” said Mueller.

“It has, however, been a challenging start to 2013 with higher fuel, airport and one-off costs, together with slightly weaker trading on UK routes. These factors have combined to produce an operating loss that is €9.4 million higher than the prior year.

“Our long-haul business continues to perform robustly, carrying forward the positive momentum from 2012. Short haul revenues were marginally ahead of 2012 on lower capacity but we expect a more difficult year ahead, particularly in the UK market.”

The carrier has been through a period of transformation which has already involved job losses.

Aer Lingus said: “While we currently have only limited visibility over booking patterns for the second half of 2013, our present level of total bookings for the remainder of 2013 is ahead of the equivalent level at this time last year. The indications are that the long-haul market is strong enough to absorb the additional capacity we have introduced.

“Trends identified in Q1 2013, including higher airport charges, the strength of long haul and the softness in GBP and our UK market have the potential to remain a feature for the rest of the year.

“On that basis, we currently expect 2013 operating profit, before exceptional items, to be broadly in line with last year.”