Strike action is brewing for a salary increase at KLM, according to the unions FNV and CNV.

The Volkskrant reports that ground staff are demanding a pay rise of at least 10%. Unions have been negotiating for a new deal for 15,000 workers since June, including baggage handlers.

KLM is understood to offer the highest wages for ground staff and to be offering a 4% increase, backdated to March. On Tuesday, the CNV said ground staff voted “unanimously” for strike action.

The unions are expected to approach KLM with an ultimatum next week. KLM told the Volkskrant that the discussions are private.