British Airways (BA) cabin crew strikes have cost the airline £7m a day.
The three-day strike, which ended yesterday, cost £21m, but BA said it was unlikely to have much impact on its full-year earnings, the BBC has reported.
However, the airline warned that the walk-outs would continue to affect its operations this week.
Tony Woodley, joint leader of the Unite union, said: “I would like to hear BA’s board justify spending millions.”
Woodley added that Unite was still willing to negotiate with BA and urged the company to resume talks, but warned that unless the talks restart soon the four-day strike, due to begin on Saturday 27 March, will go ahead as planned, the Guardian has reported.
Asked if the second phase of industrial action will go ahead, Woodley said: “That is as it looks at the moment. I don’t think there is any doubt it will go ahead because I don’t see a willingness on the part of the company to get a settlement.”
A spokesman for BA said the firm was “always available” for talks.
A trade union source told the paper that further strike dates could be announced at the beginning of next month, although Unite has already pledged not to stage industrial action during the Easter holidays.