Too many children turn up to school without being toilet-trained or knowing how to use a knife and fork, a headteachers' leader said yesterday.

David Hart, general secretary of the National Association of Head Teachers (NAHT), said behaviour was getting worse because parents fail to teach their children basic social standards.

In his last speech to the NAHT annual conference after 27 years as general secretary, Mr Hart warned that Labour's promise to boost "parent power" could backfire.

Giving irresponsible parents more power over schools would be like "putting an alcoholic in charge of a bar", he said.

Mr Hart told reporters that schools had to spend time teaching children basic tasks.

"They are not toilet-trained. They don't know how to use a knife and fork," he said.

"That means that the teachers and support staff have got to spend their time sorting them out so that they are ready to be educated."

Mr Hart also stressed that violence in school was "completely unacceptable".

"So are verbal threats, physical threats, verbal abuse, foul language, harassment and bullying by parents towards heads and their staff," he said.

"These seem to me to be the minimum standard that our members are entitled to expect their pupils and their parents to observe.

"And by the way, giving more power to those parents who lack responsibility is like putting an alcoholic in charge of a bar."

Education Secretary Ruth Kelly has promised to give parents a bigger say in the way their children are educated if Labour wins a third term in this week's General Election.

Mr Hart said: "The Government's attempts to reinforce the role of parents is a key political strategy.

"But there is a danger that it sends the wrong message - one that has parent power, not parental responsibility, written all over it."

A Labour Party spokesman said ministers wanted parents to accept their responsibilities.

"We have got no time for parents who abuse teachers, be it verbal or physical," he said.

"Parent power is something that can be a very valuable asset to improving the education system.

"But it is as much about parents' responsibilities as their rights."