British Airways accounted for £58 million ($89 million) of the first-quarter operating loss at parent IAG, while Iberia's contribution amounted to €202 million ($263 million).
IAG gave the breakdown as it presented its first-quarter results on 10 May. The company turned in an overall operating loss of €278 million for the three-month period.
Chief executive Willie Walsh says the impact from the former BMI operation - the loss-making carrier which BA took over last year - was around £35 million.
"We're not tracking the BMI performance," says Walsh. "We're just looking at it, to give a rough estimate as to what it was."