Foreign Minister Julie Bishop has defended Australia's $20-million pledge to assist Syrian refugees after other nations at a Syria donors' conference in London promised vastly bigger sums.
After announcing the pledge at the conference on Thursday she told reporters the government did not have "a bottomless pit" of funds to draw on.
The minister also announced an extra $A5 million to assist those affected by conflict in Iraq.
Australia would also deploy 10 Australian Civilian Corps specialists to Lebanon and Jordan to help with education, water, sanitation, logistics and protection for Syrian refugees, Ms Bishop said.
Labor has slammed Australia's funding pledge as "extraordinarily low" while aid groups have called it a "drop in the bucket" when it came to what was needed to assist Syrian refugees.
UN agencies are appealing for $US7.7 billion ($A10.8 billion) to cope with the Syrian disaster this year, plus $US1.2 billion to fund national response plans by countries in the region.
Britain promised an extra STG1.2 billion ($A2.44 billion) by 2020 while Germany said it would give 2.3 billion euros ($A3.6 billion) by 2018 and Italy pledged $US400 million over the next three years.
The US said it would donate an extra $US925 million ($A1.3 billion).
Smaller nations at the conference also announced pledges that dwarfed Australia's, with Norway for example giving $US1.17 billion over the next four years.
When asked by reporters about Canberra's $20 million pledge Ms Bishop said Australia had been giving humanitarian assistance to that cause since 2011.
"A number of countries are making a pledge for the very first time. Australia has been contributing from the outset."
Ms Bishop said Australia was also making a significant military contribution targeting the Islamic State group to end the conflict in Syria and Iraq and that was expected to cost $A400 million this financial year.
Australia had also pledged to permanently settle 12,000 Syrian refugees at an estimated cost of $A830 million over four years, the minister said.
The overall commitment to those conflict zones - military, humanitarian and refugee settlement - would therefore be over $A1.5 billion to date and constituted one of Australia's largest ever crisis responses, she said.
"That was a significant contribution by any measure."
Ms Bishop said Australia was also looking at an assistance package to help Jordan and Lebanon cope with the burden of the many Syrian refugees they hosted, and that would involve further funding.
She denied that was a late addition to Australia's commitment at the conference prompted by potential embarrassment on the world stage over its funding pledge.
She said aid groups who criticised the funding pledge should say "where they would like me to cut funding in order to provide more".
"This is not a bottomless pit."
Opposition foreign affairs spokeswoman Tanya Plibersek has criticised the $A20 million pledge as "extraordinarily low" and suggested the government should scrap a "dumb plebiscite" on same-sex marriage and divert the $A160 million in savings to Syria instead.
