Two former British prime ministers on Saturday warned the country’s current leader Boris Johnson against cuts to foreign aid spending.

David Cameron and Tony Blair urged Johnson not to commit to a proposed 0.2 percent cut to the UK’s £15 billion ($20 billion, EUR17 billion) international development budget.

The UK has proposed the cuts to pay for coronavirus costs but Cameron and Blair cautioned the move would jeopardise Britain’s “soft power” status around world, the Daily Telegraph reported.

The two former prime ministers also warned Johnson risked undermining the UK’s presidency of the G7 before it begins next year.

Blair praised the impact of British spending abroad in recent decades which he said was “measured literally in millions of lives”.

“This has been a great British soft power achievement. It isn’t about charity. It’s enlightened self-interest,” he said.

Cameron called abandoning Britain’s overseas aid spending a “moral, strategic and political mistake”.

“I hope the PM will stick to his clear manifesto promise, maintain UK leadership and save lives,” he added.

Blair , a former prime minister from the UK’s left of centre Labour Party, led his country from 1997 until 2007. He committed Britain to meeting a UN target of 0.7 percent in spending on foreign aid in 2005.

Cameron, from Johnson’s own centre-right Conservative Party, served in the office from 2010-2016, and delivered on the overseas spending pledge made by his predecessor in 2013.

General Lord David Richards, UK chief of defence staff until 2013, said it was in the UK’s interest “to be as generous as possible”, adding that spending on aid was “much cheaper than fighting wars”.

UK finance minister Rishi Sunak is due to address the UK’s spending in a Comprehensive Spending Review on Wednesday. The review is expected to be heavily impacted by the coronavirus pandemic.

The UK has already cut £2.9 billion from its foreign aid budget for the rest of 2020 to avoid exceeding the 0.7 percent target.