DUBLIN (Reuters) -A U.S. court ruled that Booking.com violated the Computer Fraud and Abuse Act by accessing part of Ryanair's website without permission, court documents showed.

The Irish airline, Europe's largest by passenger numbers, said the ruling would help end unauthorised screen scraping by booking sites.

Booking.com said it was disappointed with the decisions and planned to appeal.

Ryanair has in recent years launched a series of legal actions against third-party booking platforms that resell its tickets without permission.

It says the companies, which use screen-scraping software to find and resell tickets, add additional charges and make it difficult for the airline to contact passengers.

A jury in the District Court of Delaware unanimously found that Booking.com violated the Computer Fraud and Abuse Act and that it had induced a third party to access parts of Ryanair's website without authorization "with an intent to defraud," the verdict issued late on Thursday said.

The court also rejected counterclaims by Booking.com that Ryanair had defamed the booking platform and that the airline was engaged in unfair competition.

"We maintain that allowing customers to access and compare fares across the travel industry promotes consumer choice," a spokesperson for Booking.com said in an emailed statement.

Ryanair, which has in recent months signed deals with a number of online travel agents for the authorised resale of tickets, said it hoped the ruling would set a precedent.

"We expect that this ruling will end the internet piracy and overcharging perpetrated on both airlines and other travel companies and consumers by the unlawful activity of OTA (online travel agent) Pirates," Ryanair Chief Executive Michael O'Leary said in a statement.

He said he hoped the ruling would force consumer agencies across Britain and Europe to take action to outlaw illegal screen scraping and overcharging of consumers for flights and ancillary services.

(Writing by Conor Humphries; Editing by Susan Fenton)