Britain will apologise for shipping thousands of poor children, often without the knowledge of their parents, to its former colonies during the 20th century, the government said today.

Under the Child Migrants Programme, a policy which ended 40 years ago, many poor children were sent to Commonwealth countries, mainly Australia and Canada, with promises of a better life.

But according to the charity the Child Migrants Trust, many of the 7,000 migrants sent to Australia ended up being abused, dumped in institutions or used as labourers on farms against their wishes.

During the enforced resettlement policy, which ran from 1930 to 1970, some migrant children were wrongly told their parents were dead. Many parents did not know their children, some of whom were as young as three, had been sent to Australia.

The chairman of a parliamentary committee on health which looked into what happened said Prime Minister Gordon Brown wrote to him to confirm he would issue an apology in the new year.

According to the letter, extracts of which were published by the BBC, Brown told him: "the time is now right" to apologise for the actions of previous governments.

"It is important that we take the time to listen to the voices of the survivors and victims of these misguided policies," Brown said.

Schools Secretary Ed Balls told Sky News: "I think it is important that we say to the children who are now adults and older people and also to their offspring that this is something we look back on with shame.

"These are children who were shipped out of the country, often without their parents even knowing, who went on to be labourers thousands and thousands of miles away, who suffered physical and sometimes sexual abuse.

"It was something that was sanctioned by governments and that is no way to treat children," he said.

Brown's office said Australia's Prime Minister Kevin Rudd intended to issue an apology for mistreating British migrants still living there.

He will say sorry as part of a national apology to the "Forgotten Australians", British media reported.

Britain's health department said the government was discussing the issue with Australia, charities and the families involved.

"We will undertake a period of dialogue with those affected, prior to a formal apology. We plan to make a more detailed announcement early in the new year," a spokesman said.