Trade union Unite is to ballot members over possible industrial action among staff at Glasgow airport.
Staff working for International Consultants on Targeted Security (ICTS), which provides baggage screening services, are in a pay dispute with the firm.
A recent pay offer by ICTS was rejected by 77% of Unite members, according to the union.
It said the offer would have left workers performing exactly the same roles for the company based at Edinburgh airport earning 9 pence an hour more than workers based at Glasgow.
Unite also claimed ICTS workers at Glasgow have had bank holiday and shift allowance supplements removed from the pay offer despite Edinburgh airport workers having received a pay award in May involving double time on bank holidays and time and a half for working unsociable hours between 10pm and 4.30am.
At talks with ICTS in May, management had committed to bridge the gap between Glasgow and Edinburgh rates, Unite said but the union claimed the firm reneged on the deal in June.
Unite regional officer Pat McIlvogue said: “Unite has continually attempted to seek remedy with ICTS management to avoid a dispute. These requests have been met with either no response or delaying tactics.
“ICTS is a strong and profitable multi-national company. There can be no doubt that it can afford to provide a decent pay rise for its employees at Glasgow Airport in line with rates and conditions at Edinburgh Airport.
“We believe it is reasonable that Glasgow Airport ICTS workers should be treated no differently from fellow workers at Edinburgh Airport doing exactly the same job. This is a simple question of fairness.”
“ICTS has agreed to ACAS talks on 9th August and Unite remains hopeful that a remedy can be found before then.”
“However ICTS management should be under no illusions of the determination of our members to get what they rightfully deserve, which is parity with their colleagues in Edinburgh.”
“ICTS is the only employer within the Glasgow Airport campus where Unite has failed to reach an agreement on pay for 2018-19. We call on ICTS to get back round the table and offer a proposal on pay that is worthy of our members consideration.”