The Moriarty Tribunal has been set a strict deadline to finish questioning its final witness, mobile phone expert Michael Andersen.

The Payments to Politicians Inquiry was told that Professor Andersen would have to complete his evidence by Friday of next week, or face a delay in returning to the witness box in Dublin until the second half of next year.

The firm schedule for dealing with Mr Andersen was reported to the Tribunal by former Justice Minister and Attorney General, Michael McDowell, who was controversially recruited by the inquiry earlier this week specifically to quiz the Professor.

A challenge to Mr McDowell's involvement was continuing in the High Court as he addressed today's Tribunal hearing.

Mr Andersen agreed to appear before Mr Justice Michael Moriarty's 13-year long proceedings after securing an indemnity over issues relating to his evidence.

The indemnity was granted by telecoms tycoon Denis O'Brien, who is a key figure in the tribunal probe.

Previously, Mr Andersen had refused to give evidence over a period of eight years because the Government had not indemnified him against possible third-party legal action, as well as costs.

But earlier this year he told the Tribunal that indemnity had been secured through Mr O'Brien and that he was in a position to ‘correct many misconceptions’ about his part in the granting of Ireland's second mobile phone licence in 1995.

Mr Andersen acted as a key advisor to the government when the licence was handed to a consortium headed by Mr O'Brien.

The Tribunal has been examining possible links between Mr O'Brien and former Fine Gael high-flyer Michael Lowry, who was Communications Minister when the licence was granted.

Both men have denied any links over the licence issue.