Li's comments appeared to be the first clear timeframe for finishing the code of conduct. Talks have dragged on for years, with China accused of delaying progress as it prefers to deal with less powerful countries on a one-on-one basis.

Ownership of islands and waters in the South China Sea is disputed by several nations.

China, which claims virtually all of the sea, has established military positions on disputed outcrops and intimidates fishermen and naval vessels from rival countries.

Tensions have soared with fellow claimants such as Vietnam, the Philippines and Taiwan, as well as the United States, which has traditionally been the dominant military power in the area.

Beijing and the 10-member Association of Southeast Asian Nations (ASEAN) have for years sought to hammer out a code to govern disputes in the disputed waters, but the process has moved slowly.

Speaking in Singapore ahead of the opening of an ASEAN summit, Li said: "It is China's hope that the (code of conduct) consultation will be finished in three years' time so that it will contribute to enduring peace and stability in the South China Sea."

"We are not and we will not seek hegemony or expansion. That is something that we will never do," he added.

"What we hope is to have a harmonious relationship with our neighbours."

There have been small signs of progress in recent months.

China and Southeast Asian nations announced in August that they had agreed on their initial bargaining positions as they work towards a code.

While both sides hailed it as a vital step, critics said that some of Beijing's proposals in the agreement were clearly aimed at expanding its influence in the region at the expense of Washington.

Navies from China and Southeast Asia also staged their first joint drills last month in the South China Sea -- which is criss-crossed by busy shipping lanes and home to abundant natural resources -- in an effort to ease tensions.

Opposition has weakened in many parts of Southeast Asia to China's aggressive behaviour in the waters in recent years, with countries keen to attract investment from Beijing and worried about US commitment to the region under President Donald Trump.