The Chinese government signed agreements today with the 10 countries of Southeast Asia to prevent open conflict over long-disputed areas of the South China Sea and to establish the world's largest free trade zone over the next decade.

The two deals, approved at a summit in Phnom Penh, Cambodia, of the Association of Southeast Asian Nations (ASEAN), underscored China's growing influence in an area of the world worried about the rising military and economic strength of China but nonetheless eager to develop good ties with the giant neighbor. The meeting also demonstrated Beijing's increasing willingness to take a leadership role in international affairs.

After years of negotiations, the association -- composed of Brunei, Burma, Cambodia, Indonesia, Laos, Malaysia, the Philippines, Singapore, Thailand and Vietnam -- reached agreement with China on a nonbinding declaration intended to reduce the chances of military confrontation over the Spratly Islands and other disputed areas.

Located amid busy sea lanes and rich fishing waters and believed to be rich in oil and natural gas, the largely uninhabited islands are claimed in part or in whole by the Philippines, Brunei, Malaysia and Vietnam, as well as by China and Taiwan. Those nations have come close to war over the territory on several occasions in recent years, and in August, Vietnamese troops based on one islet fired warning shots at Philippine military planes.

In the declaration, all the parties agreed to exercise self-restraint in any activities that could touch off a conflict, such as settling the islands, and to give advance notice of any military exercises. The accord also called for future talks among members of the group. But it fell short of laying down the detailed, binding code of conduct that negotiators had made their goal.

Problems also remain unresolved on the economic pact. China and the Southeast Asian nations agreed on a framework to set up a vast free trade area that would boast a total gross domestic product of nearly $2 trillion. But negotiations scheduled to begin next year are expected to be difficult because many in Southeast Asia view China as a competitor sucking away foreign investment.

China can manufacture many products more cheaply than Southeast Asia can, and its market of 1.3 billion people dwarfs the scattered markets of its ASEAN neighbors, which cover about 500 million people. But the Chinese government has argued that the free trade area it has proposed would boost exports on both sides by half and result in faster growth for everyone.

"Nearly a year after China's entry into the WTO, facts have shown that economic growth in China has not come about at the expense of the development of others," Chinese Premier Zhu Rongji told the other leaders. "On the contrary, it has become an important pillar and stimulus to the East Asian economy as a whole."

Under the agreement, the more developed of the member nations would cut tariffs first, to between zero and 5 percent on most goods, and the other nations would follow over the next decade.