China has warned "external forces" not to get involved in its maritime disputes with neighbouring countries over the South China Sea.
In comments apparently directed at the US, Premier Wen Jiabao said that the disputes should be resolved by "relevant sovereign states".
Mr Wen spoke at a regional summit in Bali that US President Barack Obama is also attending.
But other nations want the contentious issue to be tackled at the forum.
The South China Sea contains some of the world's busiest shipping lanes, as well as oil and gas reserves.
China claims a huge U-shaped area of the sea - a claim that overlaps areas which Vietnam, Malaysia, the Philippines, Taiwan and Brunei say belong to them.
China's increasingly assertive behaviour over its claim in recent months has alarmed several of its neighbours.
They are keen to negotiate with China as a bloc - but China prefers to tackle the issue through bilateral negotiations, and it does not want the US involved at all.
"External forces should not use any excuse to interfere," he said in a speech carried by state news agency Xinhua.
"The dispute on the South China Sea is a matter that been going on for years. It should be resolved by the relevant sovereign states through friendly consultation and discussion directly."
Mr Obama, who is on a nine-day tour of Asia, said that the summit provided a good arena to work on the issue of maritime security.
On Thursday in a speech to the Australian parliament, he pledged increased US engagement with the region and a strong military presence, including the deployment of US Marines to Darwin in Australia.