The union Unite says baggage handling company Swissport has launched a consultation on redundancies at Belfast City Airport.
It comes after Flybe, which operated the majority of flights from the airport, went into administration last week.
Unite says up to 95 workers - over half of Swissport's staff at the airport - could face compulsory redundancy by 11 April.
The development comes as Belfast City Airport announced that Eastern Airways will begin to operate up to seven flights a week from Belfast to Southampton.
The route was one of those previously operated by Flybe.
On Wednesday, former Flybe staff and workers including Swissport staff held a rally at Stormont calling for ministers to intervene to save jobs.
George Brash from Unite said: “Swissport has informed Unite that they are initiating a 30-day consultation on job-losses at Belfast City Airport.
“As many as 95 workers – more than half their workforce at the airport – face compulsory redundancy by 11 April.
“This is devastating news for the workers and comes only days after Swissport bosses placed staff at city airport on a 14 day unpaid lay-off.”
It comes as negotiations to save routes previously operated by Flybe continue.
Katy Best from Belfast City Airport said Eastern Airways will resume the “popular” Southampton route from 23 March.
“This new service to be operated by Eastern Airways will importantly reconnect NI with the south coast of England,” she said.
“Eastern Airways commenced its six-times weekly service from Belfast City to Teesside International Airport on Monday of this week and we look forward to further building upon this route network with the airline.”
Roger Hage from Eastern Airways said: “We are ensuring Southampton is reconnected to the regions throughout England, Scotland and Northern Ireland.”
It comes after Scottish airline Loganair stepped in to safeguard two routes in and out of Belfast - to Aberdeen and Inverness.