BRUSSELS, May 30 (Reuters) - Alphabet's Google, Amazon and Airbnb won the backing of Europe's top court on Thursday in their fight against an Italian rule requiring them to provide information on themselves.

The dispute between the companies and Italian authorities centered on provisions adopted in 2020 and 2021 mandating online service providers operating in Italy to sign up to a register and submit various types of information, as well as paying a financial contribution or risking a fine.

The companies had challenged the requirement, saying it was contrary to EU legislation which says online service providers are only subject to the rules of the country where they are established, while countries where they provide a service must refrain from applying their laws.

"A member state may not impose additional obligations on an online service provider established in another member state," judges in the Luxembourg-based Court of Justice of the European Union (CJEU) said.

"Italy cannot impose on providers of those services established in other member states additional obligations which, although required for the provision of those services in that country, are not imposed in their member state of establishment," they said.

Both Google and Airbnb have their European headquarters in Ireland and Amazon in Luxembourg. U.S. online travel services provider Expedia, based in Spain, also objected to the requirement.

The ruling is final and cannot be appealed.

The cases are C-662/22 | Airbnb Ireland, C-667/22 Amazon Services Europe, C-663/22 Expedia, C-664/22 Google Ireland, C-666/22 Eg Vacation Rentals Ireland and C-665/22 Amazon Services Europe. (Reporting by Foo Yun Chee Editing by Bernadette Baum and Ana Nicolaci da Costa)