EU funding for farmers, scientists and other projects will be replaced by the Treasury after Brexit, Chancellor Philip Hammond has said.
In a move which could cost up to £6bn a year, the Treasury will guarantee to back EU-funded projects signed before this year's Autumn Statement.
Agricultural funding now provided by the EU will also continue until 2020.
But critics said the guarantee does not go far enough and there was "continued uncertainty".
Voters backed leaving the EU in the 23 June referendum but Prime Minister Theresa May has indicated the UK government will not trigger Article 50, which would begin a two-year process to leave, during 2016.