Easyjet is facing court action in Paris after allegedly breaking French labour laws.
French officials have accused the airline of failing to declare 170 staff employed at Paris Orly airport between 2003 and 2006.
Reports claim Easyjet could be liable for 10m euros in unpaid social security contributions.
Easyjet argues that because the staff were hired under British contracts, they were not subject to French rules.
The case is being heard in court on Friday, with a judgement expected a few weeks later.