One of the most senior Irish officials in Brussels, Mr John Temple Lang, has asked for early retirement from the European Commission in protest over delays in reforming the Commission's merger proceedings.

The resignation of a senior EU official over a policy issue is a rare event and the departure of Mr Temple Lang, regarded as the doyen of Irish lawyers in Brussels, has startled both the Commission and the Community. In May he was appointed Hearings Officer in the Competition Directorate, in effect ombudsman to look after the rights of those being investigated under the merger regulations, and is understood to have complained that promises to strengthen his office and make the Commission's merger proceedings more accountable have not been honoured.

Companies have protested at the difficulties they face in fathoming the process and getting their case across at hearings, and a report from the British House of Lords has called for the expansion of the role of a more independent hearings officer.

Earlier this year the Commission, which is perceived, particularly in the US, as toughening its stance on mergers, vetoed the huge US merger between WorldCom and Sprint and today will hold hearings on the link-up between Time Warner and AOL, and the pooling of WEMI's music interests with the former.

A Commission spokeswoman, Ms Amelia Torres, yesterday regretted Mr Temple Lang's departure and reiterated the intention to reform the whole merger system. "When Mr Temple Lang was appointed in May Commissioner Mario Monti said he attached great importance to the post and was determined to strengthen it," she said. "However it cannot be done in a few weeks . . . . There is no suggestion reform is off the agenda."

The Commission's chief spokesman, Mr Jonathan Faul, paid tribute to Mr Temple Lang's "long and distinguished service to the Commission" and wished him well for the future. Mr Temple Lang (63) was formerly in charge of the Competition Directorate's dealings with the telecommunications and media industries. He is known to have been close to both the current Irish Commissioner, Mr David Byrne, advising him, among other issues, on the appointment of his cabinet, and to the former Competition Commissioner, Mr Peter Sutherland.

He joined the Commission in 1974, serving for many years in the Legal Service. Previously, he was a partner in McCann, Fitzgerald in Dublin. He is a professor of law in Trinity College, Dublin, and a senior visiting research fellow in Oxford University, and has contributed over the years to the work of the Institute for European Affairs.

If Mr Temple Lang now returns to work in the private sector, Commission rules require that he must clear with them in advance any appointment which would overlap with his former competition responsibilities. His experience and standing mean he is unlikely to be short of offers.