Iain Duncan Smith has defended his decision to educate his children in the private sector.

The Conservative leader was challenged over the schooling of his own family after he pledged himself to a new "mission" of equal educational opportunities for all pupils.

In a major speech on Tuesday, Duncan Smith committed the Tories to ensuring that children from the poorest areas have the same chances as those from better-off areas.

"The best thing we can do for those children is to give them an opportunity out of their circumstances," he told the BBC.

But he was forced to defend his decision to send his son to Eton. "Parents send children to private schools because they cannot get the quality they need from the state sector," he said.

"My children have been to both state and private school and they were in a school at one stage which has a huge number of children that do not speak English as their first language."

He added: "I am not here to debate what my children do but one thing I do know as a principle is that every single parent in this country must have the choice to send their children to the best school that they can."

Duncan Smith said the government was interfering too much in the running of schools and preventing standards from being raised.

"The biggest problem that we've got is that the government has centralised so much of the control and direction that these schools now operate under."

He said countries on the continent benefited from a mix of private and state schools, which allowed people to choose those with the higher standards.

It was "unutterably negative and...defeatist" to say that standards couldn't be raised in inner cities, the Conservative leader said.