The annual regional forum of the 10-member Association of Southeast Asian Nations (ASEAN) has opened in Brunei with US Secretary of State John Kerry and his Russian counterpart discussing their positions on the war in Syria.

Kerry said on Tuesday after meeting Sergei Lavrov that Washington and Moscow were committed to holding a peace conference on Syria but that it would likely take place after August, the AFP news agency reported.

Kerry said they both agree that "the conference should happen sooner rather than later" to find a peaceful solution to the Syrian war.

Moscow has backed the Syrian regime in the more than two-year conflict that has claimed nearly 100,000 lives, while Washington has said it is boosting support for the armed opposition, including arms deliveries.

Russia and Western countries have agreed to push the opponents for talks in Geneva, but they still have no agreement on the terms of the meeting.



No talks on Snowden

Kerry also said he did not have substantive discussions with Lavrov on US whistleblower Edward Snowden.

The meeting between Kerry and Lavrov follows controversy surrounding Snowden, who leaked details of a US surveillance programme.



Snowden has been holed up in a Moscow airport as he tries to seek asylum in European and South American nations. He withdrew his asylum application for Russia after President Vladimir Putin said that if he wants to stay in Russia, "he must stop his work aimed at harming our American partners".

The ASEAN summit, which brought togther 26 countries from the Asia-Pacific region and the EU, also sent a "very strong message" to North Korea on Tuesday that it must dismantle its nuclear programme, according to South Korean foreign minister Yun Byung-se.

After a meeting with China's Foreign Minister Wang Yi and Yun, Kerry said on Monday that Beijing had been "very firm" with North Korea on its need to end its nuclear programme.

"All of us are absolutely united and absolutely firm in our insistence that the future with respect to North Korea must include denuclearization," Kerry told a news conference later.

"China made it clear to me they have made very firm statements and very firm steps they have taken with respect to the implementation of that policy."



South China sea dispute

Kerry also closed ranks with Southeast Asian nations in urging substantive talks on the disputed South China Sea in comments targeted at Beijing.

Concerns have been rising that actions by China to increase its grip on disputed islets in the sea, a key corridor for regional and world trade, could lead to conflict with rival claimants.

On Sunday, the Philippines told the gathering that China was engaging in a military build-up at sea that threatened regional peace.

ASEAN has been pushing a reluctant China for talks on a set of rules governing conduct at sea meant to avert unilateral actions that could spark trouble.

"We very much hope to see progress on a substantive code of conduct to help ensure stability in this vital region," Kerry told his ASEAN counterparts on Monday.