Australia's foreign aid program will be rebuilt if Labor wins the next federal election.

Opposition foreign affairs spokeswoman Penny Wong will pledge an increase in aid funding during a speech to a conference in Canberra on Tuesday.

"Labor will, to the fullest extent that financial circumstances allow, rebuild and grow the Australian aid program in a timely manner," Senator Wong will tell the conference at the Australian National University.

Since the coalition came to power in 2013 more than $11 billion has been cut from Australia's aid program.

"These cuts are a source of international embarrassment for Australia, and are at odds with the generous spirit of the Australian people," Senator Wong will say.

The proportion of aid spending has sunk to its lowest level on record - 22 cents for every $100 of national income.

Senator Wong did not nominate a dollar figure, citing a need to look at the budget circumstances post-election.

Finance minister Matthias Cormann said the coalition would not match any pledge to increase foreign aid, arguing the government was providing appropriate levels given Australia's fiscal circumstances.

"Until such time as we get the budget back into surplus, it really is not affordable for us to meet that commitment beyond what we've made so far," he told reporters in Canberra.

Greens senator Sarah Hanson-Young blamed both Labor and coalition governments for cuts to foreign aid.

"Both sides have egg on their face," she said.

"What they've done is pinched pennies from the poor in order to justify having a bigger government budget."

Crossbench senator David Leyonhjelm said he opposed foreign aid, "except for short-term humanitarian assistance".

"Earthquakes and tsunamis, and things like that."