Striking aircraft mechanics at Serbian flag carrier Jat Airways kept the airlines' planes on the ground on Saturday for the second consecutive day.
Angered at their latest paychecks, they demanded management be sacked and called for "a fairer distribution of wages."
They also said they were angry with the board which sacked their boss just when he was about to ensure international licences allowing Belgrade mechanics to maintain planes of any international airlines, seen as lucrative work.
The JAT board said late last night it was illegal to block both domestic and international traffic and called on the mechanics to return to work or risk getting fired.
Aircraft engineers, who suspended their own strike this week, are considering joining the strike in support of their colleagues' demands, their union chief told Reuters.
JAT management, refusing to negotiate with the strikers, said it had secured an early flight to Paris and a plane to London was scheduled to take off soon.