The Spanish regulator CNMC investigates whether Amazon.com and Apple competitors have been disadvantaged in online sales of electronic products by third parties.

CNMC is looking at whether the US tech giants have imposed restrictions on third parties who want to sell Apple products via Amazon’s Spanish website. It also examines advertising techniques for Apple products.

“This behaviour can put competition at a disadvantage when selling electronic products online,” CNMC said. The supervisor has 18 months to carry out the investigation.

Amazon already indicated that it fully cooperated with the investigation. Apple hasn’t responded yet.