The money will target security and job creation rather than traditional areas such as health and education.
International Development Secretary Douglas Alexander is expected to unveil the move in a White Paper on Monday, the agency said.
The aim is to try to prevent conflicts in 20 fragile states where about one third of the poorest people in the world live.
The change in emphasis is based on what are seen as success stories in Sierra Leone and Nepal which are both coming out of long and bitter conflicts, it said.
His department will also get a new look - branded UK Aid - to try to raise the profile of British government spending on international development.
The news agency said the government would double the amount it spends at the "harder end" of aid priorities.
This includes police, security and justice systems as well as funding to provide jobs as an alternative to war for ex-soldiers.
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