By Jared Ferrie and Paul Mooney
NAYPYITAW (Reuters) - Southeast Asian foreign ministers voiced "serious concerns" on Saturday over naval clashes between Vietnam and China as the regional group's top official urged Beijing to step up efforts to advance talks on maritime security.
Foreign ministers and heads of state of the 10-member Association of Southeast Asian Nations (ASEAN) are facing a test of unity at their summit this weekend as some members express alarm over China's growing assertiveness in the disputed South China Sea and push for a strong joint statement.
Tensions ratcheted up in the past week after China positioned a huge oil rig in an area also claimed by Vietnam, with each country accusing the other of ramming its ships in the region close to the disputed Paracel Islands.
ASEAN Secretary General Le Luong Minh, who is Vietnamese, told Reuters the incident added urgency to concluding talks between ASEAN and China on agreeing a code of conduct in the resource-rich sea - a set of maritime rules to ease tensions.
But he pointedly said China's efforts to conclude the talks had fallen short of ASEAN's. Despite holding three rounds of talks since last year, the discussions had yet to focus on "substantive issues," he said.
"We need efforts on both sides," he said in an interview on the sidelines of the summit in Myanmar's capital, Naypyitaw.
"On ASEAN, we have made great efforts. We need efforts on the part of China."
Tensions over the sea, which is claimed in part by four ASEAN members as well as China and Taiwan, have strained the group's unity in recent years, resulting in an embarrassing breakdown of a summit in Cambodia in 2012.
In their statement, ASEAN foreign ministers on Saturday called for "an early conclusion" of the code of conduct and expressed concern about "increased tensions in the area".
At the summit, which ends on Sunday, countries including Vietnam and the Philippines are pushing for a strong statement, while others - mindful of China's economic weight - are reluctant to directly criticize Beijing, diplomats say.
Myanmar, which is chairing ASEAN for the first time this year, signaled a softer approach to China.
Myanmar's government spokesman, Ye Ht, said ASEAN and China have a "very good relationship" and both recognize China's continued growth as a political and economic power should not be marred by conflict with its neighbors.
"China is not only big friends with Myanmar, but China is also the biggest trade partner with most of the ASEAN countries," he told reporters in Naypyitaw. "So China's peaceful rising is very important for the ASEAN region."
Both Vietnam and staunch U.S. ally the Philippines have insisted the South China Sea be discussed at the summit.
Philippine diplomats told Reuters some member states were opposed to issuing a separate statement on the latest South China Sea dispute or mentioning the tensions in the final communiqué due to be released on Sunday.
China says territorial disputes should be discussed on a bilateral basis. It claims the entire South China Sea, putting it in conflict with Taiwan, Vietnam, the Philippines, Malaysia, and Brunei. The last four are ASEAN members.
Speaking to reporters in Manila, Philippine President Benigno Aquino rejected calls from China for bilateral talks to resolve territorial issues and said dialogue will not resolve the issues that are also affecting other regional countries.
Tensions spiked in another part of the South China Sea over the past week when Beijing demanded the Philippines release a Chinese fishing boat and its crew seized on Tuesday off Half Moon Shoal in the Spratly Islands, which both countries claim.
(Additional reporting by Nguyen Phuong Linh in HANOI, Martin Petty in BANGKOK and Manuel Mogato in MANILA; Editing by Stuart Grudgings and Sophie Hares)