Ryanair has not established any clear evidence of wrongdoing that would justify the identification of anyone who posted material on a website set up to allow the airline's pilots communicate with each other, the High Court was told yesterday.

Michael Cush SC, counsel for the British Airline Pilots Association (Balpa), said the airline had no evidence of any person or pilot being affected by any posting on the Ryanair European Pilots' Association (Repa) website. He said site users should have the right to "speak one's mind" anonymously and in general, he argued, the airline's action must fail.

However, Richard Nesbitt SC, for Ryanair, said the airline had a right to investigate claims that its employees were being intimidated and bullied.

The submissions were made on the sixth day of proceedings where Ryanair is seeking to identify persons engaged in communications on the Repa website.

The action is against Neil Johnston, an official with the trade union Impact, the Irish Airline Pilots Association (Ialpa) and Balpa.

The company has claimed that pilots considering re-locating to Dublin to operate the new 737-800 aircraft were intimidated and threatened. It says the defendants have a duty to name persons identified by the codenames "ihateryanair", "cantfy-wontfly" and others on the Repa site that it claims was established and is controlled by Ialpa and Balpa. The defendants deny the claims.

Mr Nesbitt said the airline had seen some of the postings, including one that referred to the slashing of tyres, and had a duty to protect its staff as well as its business interests. "The only way to resolve this was to get the names," he added.

Earlier, Trevor Philips, a retired pilot and Balpa official, who was one of the moderators of the website, said airline pilots "do not go around slashing tyres". There was "nothing sinister" in that particular posting, he told Mr Nesbitt.

The case is expected to conclude before Mr Justice Thomas Smyth today.