The homework debate takes place on Radio 4's Today programme

He defended the government's policy of encouraging parents to read for 10 minutes with children as young as four after school.

The research paper, which was presented to a British Psychological Society education conference in Exeter, suggests homework might not always be a good thing.

And one of the authors says that teachers who set homework for younger children could be overloading their pupils and causing unnecessary tensions within families.

The paper says that although there are proven educational benefits to giving homework to secondary school children, this is not the case with primary children.

"I think it's rather sad that this piece of research comes up with statements like 'homework is not always a good thing'," Mr Woodhead told BBC Radio 4's Today programme.

"Well of course it is not always a good thing - it depends on the quality of homework that is set. Homework can create tensions in the family, but so can sending children to bed cause tension to the family."

Adults had a responsibility to teach children, Mr Woodhead said. "Most of the parents I talk to and, most of the teachers in the schools I visit, think that this kind of additional learning is an excellent thing."

'No evidence'

Compiled by Dr Richard Cowan and Dr Susan Hallam of the University of London's Institute of Education, the paper reviews existing research on homework from across the world.

It conflicts with the government's policy of encouraging primary schools to set homework. The Education Secretary, David Blunkett, has issued guidelines calling for four and five-year-olds to do 10 minutes of reading, and 10 minutes of other homework, a day.

Dr Cowan said: "The research shows that a lot of parents want to help their children with homework, but if they already have a difficult relationship then the process of sitting down to do homework can cause even more tension.

"A lot of people believe that the benefits of homework have been clearly demonstrated, but at primary level there's no evidence to support this.

"We are talking about young children who come home from school exhausted. If you overload them, then their performance will decline."

The paper's other findings include:

• Girls spend more time than boys on homework.

• Listening to music while doing homework seems to help pupils concentrate.

• There is little evidence that homework develops responsibility in pupils.