The State-owned port company in Limerick has suspended its chief executive, Brian Byrne, on foot of serious allegations of impropriety a local businessman has made against him.

Mr Byrne, who denies the allegation, said he received a phone call in his car after the close of business last night from the chairman of the Shannon Foynes Port Company, businessman Kieran MacSweeney.

Mr Byrne said that Mr MacSweeney suspended him during the course of this conversation. Mr Byrne believes the suspension is indefinite.

"I'm shocked and disappointed at the direction that this development has taken. I have a proud and unblemished career. I have a very strong record of achievement in the port company since I joined it four years ago. I absolutely refute any and all of these spurious allegations," he said.

Limerick haulage contractor Brian Cosgrave made verbal allegations to Mr MacSweeney about Mr Byrne and another senior member of the port company some time ago. Mr Cosgrave set out his claims in writing this week to an investigation committee chaired by a retired civil servant, Michael Guilfoyle.

The suspension followed a board meeting last night at which the committee's work was discussed. There was no immediate comment from the company and the position of the other individual against whom claims were made was unclear.

Mr Byrne thanked "those directors who have understood my position and supported my role" and said he worked in the company and the State's best interests. "I will take the necessary legal steps to vigorously and trenchantly defend my good name. I'd like to thank all of the staff and employees of the company for their hard work and loyalty over my years as chief executive officer."