Heathrow Express train drivers may walk out on strike next month in a dispute over union recognition.

Members of the Associated Society of Locomotive Engineers and Firemen (Aslef), the train drivers’ union, are to be balloted over the next few weeks on industrial action and a possible ban on overtime.

Heathrow Express insists its 280 employees want representation by both Aslef and its “independent” staff association.

Alsef said it would resist moves to grant it parity of negotiation with the association.

Aslef wants to retain exclusive recognition rights for its members.

Heathrow Express runs the 15-minute service between the airport and London’s Paddington Station 150 times a day.

Should the ballot take place, it will close on 18 September and under current employment legislation law, strike action could begin a week later.