The £4 billion reduction to the budget was "deeply irresponsible" at a time when developing countries are responding to the Covid pandemic, according to Scotland's international development minister Jenny Gilruth.
Nicola Sturgeon also branded the changes “deplorable.”
The decision to cut Britain’s overseas aid budget from 0.7 per cent of gross national income to 0.5 per cent was set out in today's spending review and breaks a Tory manifesto commitment made only a year ago.
“This is a deplorable decision by the Prime Minister and UK Government," Ms Gilruth said.
“The Covid-19 pandemic has caused untold distress and damage to people and economies across the world, and as the UK Government’s primary source of development assistance, the Foreign, Commonwealth and Development Office must do all it can to help the world’s poorest countries to both respond and to build back fairer."
The Prime Minister pledged earlier this year to abide by the legally-binding commitment to spend 0.7 per cent of gross national income on overseas development aid.
But concerns were raised after the merger of the Department for International Development with the Foreign and Commonwealth Office.
The economic impact of Covid already means that fewer funds will be available as gross national income slumps.
Ms Gilruth said: “It is a dangerous and deeply irresponsible move at a time when the world is responding to a pandemic that does not respect borders.
“Turning its back on the commitment, and in turn abandoning some of the world’s poorest communities, demonstrates the UK Government is only concerned with pursuing self-interest.
The 0.7 per cent figure was first adopted internationally as a target by the UN general assembly in October 1970 following a World Bank report recommendation. In 2005, the 15 countries that were members of the European Union by 2004 agreed to reach the target by 2015, but few in practice did so.
First Minister Nicola Sturgeon added: “The cut to the overseas aid budget is a political gesture to the right wing of the Tory party, and the price of it will be paid by some of the poorest people in the world. Deplorable indeed.”