Jamie Cann, 52, MP for the Suffolk town of Ipswich, failed a roadside test after being stopped as he drove to a friend's house at lunchtime on Saturday.

Former teacher Mr Cann admitted being over the limit and speeding, but said his last drink was beer - the night before.

He said: "I have never, ever, knowingly driven over the alcohol limit and, indeed, I never drive if I have had more than a pint of beer."

Caught speeding

Mr Cann, elected MP in 1992, said he had attended a political meeting in a local pub just hours before the test, but drank only orange juice.

He was stopped as he drove at 40mph through a 30mph zone in Martlesham, near Ipswich.

Mr Cann added: "To my horror I was over the limit.

"That is the only time I have been over the limit in 25 years driving and I did not have a clue that I was.

"I hope others will learn the lesson, namely that you can't assume because of the passage of a number of hours and a period of sleep that you are not still over the limit."

Discipline 'unlikely'

Mr Cann's election agent, John Mowles said: "Obviously it was something left in his system.

"Jamie has always said you should not drink and drive and if he had had a drink, he would not drive."

A Labour Party spokesman said any disciplinary action against Mr Cann was "very unlikely".

The former leader of Ipswich Council was released on police bail to appear before Deben magistrates near Ipswich on 7 September.