Justin Welby said the UK should stand by its commitment and send "a strong signal that the UK is a reliable partner for long-term economic, social, environmental and educational advancement across the globe."
Chancellor Rishi Sunak is expected to pare back the overseas aid budget from 0.7 per cent of national income to 0.5 per cent - amounting to a saving of about £4bn a year - in his spending review on Wednesday.
However the plans have met with opposition from former prime ministers David Cameron and Tony Blair, who both described it as a “strategic mistake”, as well as major UK charities such as Unicef and Save the Children.
The archbishop told the Observer: "I've seen the good done by UK aid around the world.
"Our generosity and strategic input has genuinely changed lives and communities for the better. In his teaching, Jesus tells us we mustn't limit our concept of neighbour simply to those close by to us. We need to heed that message in the tough times as well as the good.
"A global recovery from the economic consequences of the pandemic requires a global response. Keeping our aid commitment is a strong signal that the UK is a reliable partner for long-term economic, social, environmental and educational advancement across the globe."
The government has pointed out that the legislation enshrining the 0.7 per cent target in UK law explicitly acknowledged it might not always be met.
Mr Welby’s intervention came as it was confirmed the archbishop will take a three-month sabbatical from his duties from May next year.
Lambeth Palace said it was “normal practice” for the archbishop to take time off and that the break would be used for “reflection, prayer and spiritual renewal".
Mr Welby will remain in regular contact with his staff while away and is expected to resume his official duties in September 2021.
Additional reporting by agencies
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