Only three of Scotland's 53,000 primary and secondary teachers were sacked on grounds of incompetence last year despite pledges by previous ministers to clamp down on poor performance in the classroom.

According to figures obtained by The Herald under Freedom of Information legislation, the only local authorities to remove a teacher last year because of poor performance were East Ayrshire, Glasgow and Perth and Kinross. Only one teacher in Scotland was demoted because of poor teaching - again in Glasgow.

The figures were seized on by heads who said procedures for sacking incompetent staff were not being used effectively.

In the past, council education committees had responsibility for sacking bad teachers, but the process was condemned for being too complex and unwieldy and the power was passed to directors of education.

However, a Herald investigation last year revealed that since 2000 only nine teachers had been sacked across Scotland - seven of them in Glasgow.

Following the revelations, Peter Peacock, education minister under the former Scottish Labour-led administration, demanded incompetent teachers be given a year to improve or face the sack. However, Bill McGregor, general secretary of the Headteachers' Association of Scotland, which represents secondary heads, said the system was "clearly not working".

"We can see from the latest figures that we are still in exactly the same position as we were in before. There is a reluctance for local authorities to take action to deal with this by dismissal. Directors of education have the powers, but no-one wants to be the first one to get to grips with this problem on any scale.

"While the great majority of teachers are excellent and the profession is becoming more highly skilled, there are clearly more than three teachers requiring dismissal across Scotland."

However, Bruce Robertson, president of the Association of Directors of Education Scotland defended the approach taken by local authorities and said that most incompetent teachers left the profession voluntarily.

"The process of competency starts at university and quite a number of student teachers are weeded out at that stage or during their probationary period," he said.

"Where a teacher does get to the classroom and is found to be not up to the job then it is my experience that the matter rarely gets to the dismissal stage because the member of staff concerned resigns. If the writing is on the wall, people will move on."

A spokesman for the Educational Institute of Scotland agreed. "While the number of teachers removed from their posts is clearly low, many individuals will elect to leave of their own accord, or be counselled that the profession is not their best career option. Self-regulation, through professional bodies such as the EIS has always been a characteristic of the teaching profession."

A Scottish Government spokeswoman said: "It is for individual councils to make decisions about who they employ and, although we expect councils to take whatever action necessary to protect standards of education, ultimately performance management is a matter for them."