BRUSSELS (AP) — Belgian air traffic controllers continued their wildcat strike for a second day on Wednesday, forcing the cancellation of flights at Brussels airport and angering the government as the nation struggles to recover from last month's suicide bombings.

Prime Minister Charles Michel said the controllers made an "irresponsible choice" by walking out at this stage and said the government "will not be blackmailed."

Belgian flag carrier Brussels Airlines said that around 50 of its flights to and from the main international Zaventem airport were canceled.

The strike action over pensions and staffing has been brewing for months, but the stoppage came without warning Tuesday afternoon as controllers called in sick, saying they were unfit to work.

The International Air Transport Association condemned the move, calling it "a kick in the teeth for all the airline and airport staff who have worked so hard to reconnect Brussels to the world after the appalling terrorist attack just three weeks ago."

Since March 22, when 16 people were killed at the airport in two suicide bombings, the airport has been slowly trying to restore normalcy, but was taken aback by the strike.

"It is important for employment in our country, and I cannot accept that a minority makes such an irresponsible choice," Michel said.