Amid of a hard-fought election campaign, Prime Minister Kevin Rudd has been on the phone to a succession of world leaders to build an international response to the crisis in Syria.

Mr Rudd spoke with UK Prime Minister David Cameron on Tuesday night, after earlier speaking with United States President Barack Obama and regional leaders including Indonesian President Susilo Bambang Yudhoyono.

In recent days he's also talked with UN Secretary General Ban Ki-moon and French president Francois Hollande.

"We are working very closely with our partners, our friends and allies across the world at this time of growing crisis in the Middle East and Syria in particular," he told reporters in Brisbane.

"Let us not forget what has happened here.

"What we have is tantamount to a crime against humanity, when you see the use of chemical weapons against civilians."

Mr Rudd said his government had formed a view there was overwhelming evidence of the use of chemical weapons.

"We have high confidence that the regime in Syria is responsible," he said.

Mr Rudd said it was incumbent on the prime minister at such a time of international crisis to be in touch with world leaders.

"When you are looking at our responsibilities on the UN security council, it is critical that we are in close contact with other members."

Mr Rudd said Australia's ambassador to the United Nations, Gary Quinlan, would take up Australia's presidency of the security council on Sunday.

"The diplomatic activity in New York is now at full speed and it is important that the international community form a common resolve on this question," he said.