Mr Brown announced the aid at Downing Street, as he met Zimbabwe Prime Minister Morgan Tsvangirai.

The money will be channelled through aid agencies and non-governmental organisations, not Zimbabwe's power-sharing government.

Some £4m will be devoted to food aid and the rest to buying text books for Zimbabwean schools.

Mr Brown said it would bring British transitional aid this year to a total of $60m (£36m).

He was speaking at a joint news conference with Zimbabwe's Prime minister Morgan Tsvangirai who defended his decision to share power with President Robert Mugabe in February.

Mr Tsvangirai said "irreversible change was now taking place in Zimbabwe towards a transition to democracy and elections".

On Saturday in London, Mr Tsvangirai was booed by Zimbabwean exiles when he urged them to return to the country.