Toddlers from 'problem families' are prevented from learning to walk by being strapped into buggies and left in front of TV sets for hours on end, according to a government adviser.

Louise Casey, who is the government's chief adviser on problem families, has claimed that children in about 120,000 troubled families lack adequate care and supervision.

She told a cross-party meeting on Sure Start children's centres and child protection in Westminster that a head teacher in one northern school had told her that some younger pupils were unable to walk, because "they are so used to being put in a buggy in front of the telly ... and one of them could not chew," reported the Sunday Times.

Casey, who is leading a new £450 million programme to help problem families, said of successive governments' attempts to tackle the problem: "Will any of those things touch those families? The answer is they haven't done yet."

National Association of Head Teachers general secretary Russell Hobby said, "It's an extreme case, but more frequently we hear of children who can't speak when they come to school."

He told the Sunday Times those children can "only grunt" and some still wear nappies at the age of five. Hobby said that issue and not being able to speak are "two most common complaints".

Last week Jackanory creator Joy Whitby argued that children under five should not be left alone in front of the television, and that there were a "glutting amount" of "noisy, meretricious cartoons" that were of no benefit to children's development.