Operating result before exceptional items was a loss of €535 million compared to a profit of €135 million previous year. It said Vueling experienced a modest increase in operating loss.
Up to 12,000 British Airways staff will be made redundant after its owner IAG racked up losses of £466million in the first quarter. Union leaders criticized the plans and said the airline should have worked to secure more government aid to avoid cutting jobs.
About 4,500 pilots and 16,000 cabin crew work for BA, which has already put nearly 23,000 staff on furlough.
Alongside the statement by IAG, BA chief executive Alex Cruz wrote a letter directly to staff pledging to "take action" in response to the worsening crisis. But because of the way some of the contracts are structured, the unexpected drop has forced many of them to hand cash over to banks even as many ask governments for multibillion euro taxpayer bailouts.
"Any money we borrow now will only be short-term and will not address the longer-term challenges we will face now".
"Balpa does not accept that a case has been made for these job losses and we will be fighting to save every single one", General Secretary Brian Strutton said in a statement. "We are a strong, well-managed business that has faced into, and overcome, many crises in our hundred-year history", he said.
Unite the Union, which also represents BA workers, said it was a "heartless decision and entirely at odds with the course of action followed by our European competitors as they seek a way through the coronavirus crisis".
BA had previously announced that more than 22,000 workers had been furloughed as part of the United Kingdom job retention scheme, taking paid leave through a government subsidy for their wages. Under the scheme, the government takes on part of the cost of retaining staff who remain on the payroll while being sent home during the crisis.
"Recovery to the level of passenger demand in 2019 is expected to take several years, necessitating group-wide restructuring measures".
The airline has axed staff numbers by a quarter as it warned of a slow recovery from the coronavirus pandemic. More than half the world's airplanes are in storage.
IAG said it expects its operating losses in the second quarter to be significantly worse.
The group repeated its February guidance that "given the uncertainty on the impact and duration of Covid-19, IAG is not now providing profit guidance for 2020" as a whole. That compared to a profit of €135m in the first three months of 2019.
More detailed results for the first quarter will be released as planned on May 7th the group said.