A White Paper to be published on Wednesday, endorsed by Tony Blair, the Prime Minister, will launch a range of initiatives. These include directing aid to Third World countries who are giving priority to their own poor people, promoting "ethical training" by supermarkets and other businesses, and launching a campaign to mobilise public opinion behind aid.
It has also found a backdoor way of increasing Britain's aid budget by hundreds of millions of pounds, despite the Treasury's freeze on public spending, and will confirm the long-expected scrapping of the official "slush fund" that financed the Pergau dam and other aid scandals under the last government.
The White Paper is the first on the subject for 22 years. It reverses the policies of the Conservatives, who, shortly after taking power in 1979, announced they were channelling assistance to the Third World to give priority to supporting British business. One senior official at the Department of International Development said yesterday: "It is going to be very different."
In her introduction to the 82-page document Clare Short, Secretary of State for International Development, stresses that Britain "has a moral duty to reach out to the poor and the needy" and says that the change of direction is designed "to make sure that the poorest people in the world benefit". It will endorse international targets to halve the proportion of the world's people living in extreme poverty by 2015.
The new policies are an important victory for Ms Short, often depicted by government spin-doctors as one of the least influential members of the Cabinet. Recently she has formed an alliance with senior ministers - including Chancellor Gordon Brown and Margaret Beckett, Secretary of State for Trade - and secured the commitment of the Prime Minister. In a foreword to the White Paper, Mr Blair says it fits in with his vision of the "giving age" outlined in his speech at party conference.
The White Paper - which has the backing of a large proportion of the new, young MPs - will also support "ethical trading", which is gaining ground in British supermarket chains, seven of which have adopted policies on the issue.
The department will set up a panel to provide expertise, and a databank to help businesses find out where to get goods that are produced in environmentally friendly ways which also respect human rights and good labour practices.
One hundred thousand summaries of the White Paper will be distributed in supermarkets, and Ms Short and George Foulkes, her Junior Minister, will tour the country to publicise it. They are pressing for Third World development to be included in the national curriculum, and are considering issuing "pledge cards" giving people advice on what they can do.
More controversially, the Government will give preference to countries which concentrate on meeting the needs of their poorest people, promote environmentally friendly development, have "accountable" governments and "bear down on corruption". These will be invited to become "partners" of the British aid programme.
The White Paper gives no details of how the long decline in the proportion of Britain's Gross National Product spent on aid will be reversed. But there will be an unprecedented increase because the hundreds of millions of pounds expected to be raised by selling the major share in the Government's Commonwealth Development Programme, will go directly into the aid budget.
So too will money released by scrapping the Aid Trade Provision, the "slush fund" that financed the construction of the Pergau dam.
The White Paper will also set up an annual meeting to vet its own performance. In her foreword, Ms Short stresses that the new agenda must be pursued as "a matter of urgency" and warns that, if it is not, "by the middle of the next century, the world will not be sustainable".
Ethical trading, page 10