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The government department responsible for overseas aid is to be merged with the Foreign Office (FCO), the BBC understands.
The move to combine the Department for International Development (DfID) and the FCO follows a review into UK aid spending by crossbench peer Lord Bew.
PM Boris Johnson is expected to confirm the move, long mooted in Conservative circles, in the Commons later.
The departments have shared a team of ministers since a February reshuffle.
BBC diplomatic correspondent James Landale said supporters of the move would argue it will focus aid spending on the UK's national interests.
But opponents would say the merger will be a waste of time and resources and reduce the priority of reducing poverty, our correspondent added.
The department now known as DfID began life under Harold Wilson's Labour government in 1964 as the Ministry of Overseas Development (ODM).
It was later merged with the Foreign Office under Ted Heath's Conservative government in 1970, but was re-established as a separate ministry by Mr Wilson after his return to Downing Street in 1974.
It was re-merged with the Foreign Office again however after the election of Conservative Prime Minister Margaret Thatcher in 1979.
The current department was again carved out of the Foreign Office in 1997 under Labour after the election victory of Tony Blair, with the new name Department for International Development.