The mud-slinging started last month when Mr Pathirana revealed that 400, 000 of the 499,000 students who sat O-levels this year, failed their exams, and accused teachers of being lazy and undisciplined.

Mrs Kumaratunga said: “Only 20 per cent of teachers do their job properly. Most students hate their teachers for not teaching them. This is one factor that led to two youth rebellions in the country.”

Some principals, many of whom say it is difficult to recruit dedicated teachers, particularly in rural areas, welcomed Mrs Kumaratunga’s speech, which dealt a “much needed shock to the collective psyche of teachers”, said one principal.

Mr MK Abeywardene, principal of Nalanda Girls Middle School, agreed. “We all need a pep talk,” he said.

Many principals complain that teachers in towns prefer to earn money by teaching at burgeoning private colleges, while in the rural areas absenteeism is high because teachers work in the paddy fields. If the teachers were doing their jobs properly, they claim, fewer children would need to go to private tutorials.

Premasara Samarathunga, president of the teachers’ union JASS, said the allegations were baseless and demoralising.

“We would have accepted the statement if it was made after conducting a systematic survey,” he said. “But to direct such allegations without any substantial proof does a lot of harm to the profession.

“There might be teachers who do not carry out their duties - we don’t deny the fact - but that does not mean that the entire profession should be condemned. ”

The incident has opened up debate on the whole education system, which is seen to be in a mess, not least because of heavy bureaucracy which makes changes within schools difficult to implement.

Teachers accuse the government of trying to blame teachers for the failings of the education ministry. They say the government has yet to come up with a plan to improve the system and to motivate teachers to stay in the profession.