Denis O’Brien has claimed remarks made in the Dáil about his personal banking affairs effectively determined a court case he had initiated against RTÉ.

The High Court has begun hearing his legal action against a number of TDs and the Dáil Committee on Procedure and Privileges.

He claims his rights to privacy and access to the courts were breached after his dealings with the IBRC were disclosed during a Dáil debate in May 2015.

Michael Cush, who is acting for Denis O’Brien, opened his case this morning by saying his client contends that was said in the Dáil by Deputies Catherine Murphy and Pearse Doherty had the effect of determining a case that was pending before the courts.

He said he had already obtained a temporary injunction preventing RTÉ from broadcasting what he considered to be confidential information about his personal banking affairs with the IBRC, but that it was effectively worthless when the TDs revealed the details.

Parliamentary debate is protected by absolute privilege, but Mr O’Brien contends that it cannot be relied on when the subject matter is before the courts.

He argues that to do so is a violation of the separation of powers between the judiciary and the legislature, and he is seeking a declaration to that effect.

This hearing is expected to take up to eight days. It will hear from Mr O’Brien on Thursday.