A recent agreement between Amsterdam Schiphol airport and airline company KLM is being investigated by the Dutch consumer authority ACM.

The controversial agreement means KLM is the only airline guaranteed a slot at Schiphol, with other airlines such as Transavia being stimulated to move to regional airports such as Lelystad.

The aim is to make Schiphol a strong and sustainable base for business traffic.

‘We were already studying the agreement to see if we could appeal it, but the details were not concrete enough,’ Steven van der Heijden, CEO of the Netherlands’ largest holiday company TUI and owner charter airline ArkeFly, told the Volkskrant. ‘We are pleased the ACW has not waited and is now investigating.’

KLM has already said its charter subsidiary Transavia is focusing its expansion of Eindhoven and Rotterdam. But British budget airline EasyJet has been trying to expand its Schiphol service for years and feels it is disadvantaged by the KLM deal.

The ACM has already visited Schiphol and is spending Wednesday at KLM.