The coalition's plan to reduce foreign aid spending by $4.5 billion will diminish Australia's security, Foreign Minister Bob Carr says.
"We provide overseas aid because it's in Australia's interest," Senator Carr said at the G20 leaders' summit in St Petersburg, Russia, on Thursday.
"We use foreign aid as a way of making Australia more secure as a nation.
"To cut back on that means you diminish Australian security."
The coalition has released policy costings which include a $4.5 billion cut to foreign aid spending over four years.
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The funds would be reallocated to three road projects in Sydney, Melbourne and Brisbane.
The coalition is expected to easily win Saturday's federal election but Senator Carr refused to be drawn on his own future in parliament if Labor loses.
"I'm only contemplating a Labor win," he said.
"Yes, against the suggestions in the polls, but a Labor win based on the fact that people will vote for jobs and their economic security not for the cuts that Tony Abbott is promising."
World Vision Australia chief executive Tim Costello says the coalition's planned cuts to foreign aid are "really cheap".
"It's very short-sighted and pretty devastating," he told reporters at the G20 where he's representing civil society NGOs.
"It's really cheap to say 'We are just going to look after ourselves - charity begins at home'.
"We can do both. This is not a good global look."
Mr Costello said the coalition should follow Britain's conservative prime minister who has said he won't balance the books on the back of the world's poor.
"It's in all of our interests to invest in health and saving lives - particularly Australia's - because the world's poor are on our doorstep," the World Vision chief said, adding increased prosperity benefited Australia through more trade and improved security.
Mr Abbott later denied foreign aid was being cut.
"We're not cutting foreign aid, we're just reducing the rate of increase," he told the Seven Sunrise program on Friday.
"Under us, foreign aid will increase at CPI until such time as the budget is back in a much stronger position."
