Risks are growing that incidents at sea involving China could lead to war in Asia, potentially drawing in the United States and other powers, an Australian think tank warned on Tuesday.

The Lowy Institute said in a report that the Chinese military's risk-taking behaviour in the South and East China Seas, along with the country's resource needs and greater assertiveness, had raised the chances of an armed conflict.

"The sea lanes of Indo-Pacific Asia are becoming more crowded, contested and vulnerable to armed strife. Naval and air forces are being strengthened amid shifting balances of economic strategic weight," report authors Rory Medcalf and Raoul Heinrichs wrote.

"China's frictions with the United States, Japan and India are likely to persist and intensify. As the number and tempo of incidents increases, so does the likelihood that an episode will escalate to armed confrontation, diplomatic crisis or possibly even conflict," they said.

The study on major powers and maritime security in Indo-Pacific Asia was published as China prepares to unveil its first aircraft carrier, perhaps this week, a development that has added to worries in the region about China's military expansion and reach.

This month, China sent its biggest civilian patrol ship to the South China Sea. That rattled the Philippines, which makes competing claims to some waters thought to hold vast oil and gas reserves.

On Monday, the U.S. Senate passed a resolution that deplored China's use of force against Vietnamese and Philippine ships in the South China Sea.

Senator Jim Webb, chair of an east Asian and Pacific affairs subcommittee of the Senate Foreign Relations Committee, said 'a growing number of nations around the South China Sea are now voicing serious concerns about China's pattern of intimidation'.

Chinese Foreign Ministry spokesman Hong Lei, speaking at a regular news briefing in Beijing, said the U.S. resolution 'did not hold water' and that countries not directly involved in the dispute should not interfere.

"Countries not involved should respect the hard work of countries actually involved to peacefully resolve the dispute bilaterally through dialogue," Hong said.

Danger zone

Ian Storey, an expert on maritime security in Asia, said the report was a 'balanced and credible assessment' of the risks of a clash in the South China Sea as 'competition over territorial claims, maritime boundaries and natural resources heats up, and as China adopts more aggressive tactics'.

"The complete absence of confidence-building measures and conflict prevention mechanisms between the various claimants suggests that it is only a question of time before an incident at sea escalates into a more serious confrontation, with worrying implications for regional stability," said Storey, a security analyst at the Institute of Southeast Asian Studies in Singapore.

Medcalf and Heinrichs said more maritime patrols and intrusive surveillance, nationalism and resources disputes would together make it harder to manage arguments over maritime sovereignty.

"All of these factors are making Asia a danger zone for incidents at sea: close-range encounters involving vessels and aircraft from competing powers, typically in sensitive or contested zones," the authors said.

The report detailed tension between Beijing and Tokyo, which stemmed from an April 2010 Chinese naval exercise near the Japanese islands of Okinawa and were exacerbated by Japan's arrest of a Chinese fisherman whose trawler had rammed a coastguard vessel.

Those incidents provoked a diplomatic crisis during which China cut its exports of crucial rare earth minerals to Japan, the United States' closest ally in the region.

Despite initial signs of warmer bilateral ties following the March tsunami and nuclear crisis in Japan, a long-running dispute over a chain of isles which are close to potentially significant oil and gas reserves simmers.

"Helicopter buzzing incidents have continued, with Japan deploring as especially insensitive an instance that occurred in the weeks following the March disaster," the authors said.

They said Beijing has caused concern in Southeast Asia over its 'core interest' claim on the South China Sea and in Australia about its possible future security behaviour, while the emergence of competition between India and China at sea is 'only a matter of time'.

New efforts were needed to build regional confidence and to involve China in a continued military dialogue with the United States and Japan, they said.

They also said maritime security hotlines were needed between the United States and China, and Japan and China, to allow real-time responses to any incidents.