ACAS has called on airline CityJet to turn up for talks with union bosses in order to avoid further strikes at London City Airport.
The industrial dispute service is mediating talks between the GMB union and Aviation Resources, an agency which employs staff on behalf of the airline.
Staff are threatening to strike over pay and employment conditions.
CityJet is needed at the talks as it must sanction any increase Aviation Resources could make.
Further talks are scheduled for next month.