The sensitive issue of land and sea ownership has overshadowed the talks in Phnom Penh.
Australian Prime Minister Julia Gillard believes the East Asia Summit is the right venue to try to sort out the problems.
Correspondent: Louise Yaxley
Speakers: Julia Gillard, Australian Prime Minister
LOUISE YAXLEY: Many of the leaders at the East Asia Summit are embroiled in territorial disputes with each other over resource rich seas and islands. Julia Gillard says they tackled those issues during their gathering.
JULIA GILLARD: We've been able to have some frank discussions about key challenges in our region, including issues involving the South China Sea and North Korea.
LOUISE YAXLEY: But Ms Gillard won't divulge what was said.
JULIA GILLARD: You've got to respect the fact that this is a closed door meeting. You would have expected leaders to put different perspectives and they did. But it was a good discussion; it was a discussion in a constructive spirit.
LOUISE YAXLEY: A United States government spokesman says president Barack Obama urged a reduction in tensions and said there is no reason to risk escalation.
But a Chinese spokesman has made it clear that China doesn't believe the issue should be on the table at summits like this.
The South China Sea was not mentioned in a lengthy concluding statement read by the Cambodian leader and strong ally of China, Hun Sen, who also took no questions, saying he was too tired.
While China is in dispute with many nations it's also a vital trading partner.
Ms Gillard presented China's premier Wen Jiabao with a photo from 1973 of Gough Whitlam meeting Chairman Mao.
It's to mark the 40th anniversary of diplomatic relations.
JULIA GILLARD: It was Gough Whitlam as opposition leader and then as prime minister who opened diplomatic relations with China. He was the subject of partisan criticism, viewed as having been I think the terminology was "played like a trout" by the then Liberal prime minister of our nation.
And it just goes to show, doesn't it, that with the perspective of history things that were controversial at the time become so much part of the norm that it's no-one who criticises them any longer. And we may well see that play out about some controversial issues in our domestic politics today.
LOUISE YAXLEY: Ms Gillard's used the summit to promote Australia's anti malaria campaign for the region.
JULIA GILLARD: We do know how to make a difference. We've made a difference to a lot of kids' lives. We've got a lot of vaccine into kids' arms and down their throats that will make a difference to them, to diseases like polio.
LOUISE YAXLEY: She's defended the Government's aid agency AusAID over allegations of corruption surrounding a malaria fund that's financed by nations including Australia.
JULIA GILLARD: I am aware of these allegations and of course like all allegations they've got to be looked at and properly worked through.
We through our aid program take a very rigorous approach to the expenditure of Australian dollars.