Esther Rantzen has been the driving force behind Childline

The move will result in the Childline helpline, set up by TV presenter Esther Rantzen in 1986, becoming part of the larger NSPCC.

It follows months of talks between the charities after Childline approached the NSPCC to help secure its future.

The charity, set up in 1986, has been struggling to raise enough cash to operate its 24-hour helpline service.

'Enormous demand'

A statement from the charities said: "Childline has helped almost two million children since it was founded by Esther Rantzen in 1986 but the challenging and competitive fundraising environment has meant that the helpline has never been able to meet the enormous demand from children."

It said the charity's incorporation as a distinct service within the NSPCC would enable it to answer many more calls from children.

The Childline name will not change and it will remain a free 24-hour service for any child or young person with a problem.

Childline's other operations will also be taken over by the NSPCC.

In Scotland, both charities are negotiating for the helpline to be operated by a third organisation, Children 1st.

The charities are entering a consultation period to finalise the details of the merger, which is expected happen early in 2006.