SIR Alex Ferguson, the Manchester United manager, yesterday said he had no plans to slow down after undergoing treatment for an irregular heartbeat.

The 61-year-old underwent the two-hour procedure at a Manchester hospital on Thursday, following a routine check-up several months ago.

Irregular heartbeats can be caused by an overload of stress but Sir Alex, famed for his fiery temper and hard work ethic, said he felt ''fine''.

Speaking at a news conference at the club's Carrington training ground, he said: ''I am fine. It was just the sensationalism of the newspapers, but there is nothing you can do about that.

''When any celebrity goes into hospital these days, someone is going to telephone the newspapers and that is what has happened.

''I have seen a doctor. He's fine and there is no problem.''

Asked whether he had any intention of cutting back on his workload at Old Trafford, the Scot said: ''No, I enjoy the work I do and it will continue.''

Sir Alex had a procedure called cardio-version, in which an electric shock is delivered to the heart to restore a regular beat. Tony Blair, who underwent the same treatment for a similar complaint in October, last night sent Sir Alex his best wishes.

An irregular heartbeat is a relatively common problem. Its main cause is a condition called atrial fibrillation, a rapid heart rate in which the upper chambers of the heart contract abnormally.

Professor Nicholas Peters, a cardiologist at St Mary's Hospital in London and Imperial College, explained: ''It is a (condition) of relatively high prevalence in the population. It is likely that is what it was.

''It is possible it was atrial flutter, which is less common.''

Sir Alex was admitted to hospital on the recommendation of a health monitoring scheme recently launched by the League Managers Association.

Some of the problems faced this year by the former Scotland and Aberdeen manager include the transfer of David Beckham to Real Madrid, a missed drugs test by United defender Rio Ferdinand, and a legal battle over a champion racehorse.