Carr hopeful of progress on Syria at G20

Foreign Minister Bob Carr has again backed any US-led strike on Syria, but is hopeful a negotiated settlement can be reached at the G20 leaders' summit in St Petersburg.

Senator Carr says the two-day forum could resolve the differences between the US and Russian over how to handle the crisis.

"Very often the moment before the dawn is the darkest," he told reporters.

"Just when sides have dug themselves in diplomatically, in well-worn positions, you can always surprise yourself and surprise the suffering people of Syria by pulling off an agreement."

Senator Carr met with his Russian counterpart, Sergey Lavrov, in Moscow earlier this week.

"I have never demonised Russia for its position on Syria," the Australian foreign minister said on Thursday.

"We've got to work with Russia to see if we can bring together the possibility of a ceasefire and a negotiated solution that sees movement towards a plural, multi-faith Syria. You won't do that without Russia."

Senator Carr insisted the US wanted a peaceful solution and President Barack Obama was reluctant to engage in more military action in the Middle East.

The foreign minister reiterated Canberra's support for any limited US strikes that didn't involve boots on the ground.

"Our assessment of the evidence, according to our intelligence community, accords with that made by the Americans," he said.

"A global norm has been violated. A nation has used chemical weapons against its own people. That breach justifies a response."

Australia has never contemplated a military role itself in Syria.

Senator Carr plans to push for a medical pact so that medicines can be distributed throughout Syria's government and anti-government zones.

Hospitals and staff also needed to be protected everywhere, he said in St Petersburg.

Obama cleared the first hurdle on Wednesday in his bid to win domestic congressional backing for punitive strikes, but is also seeking broader international support.