China said it will work with all related parties for peace and prosperity in the South China Sea after a leading Indonesian official praised China's willingness to maintain peace in Asia.

Ryamizard Ryacudu, the Indonesian defense minister, told the Raisina Dialogue 2018 in New Delhi on Thursday that the situation in the South China Sea is easing and such momentum needs to be maintained, according to the National Herald newspaper in India.

He also expressed his appreciation for "the goodwill of China to be more open and over its willingness to cooperate in maintaining the security structure in the region".

Ryacudu's comments show the sincere will of both China and ASEAN countries to work together to maintain peace in the South China Sea, Foreign Ministry spokeswoman Hua Chunying said on Monday.

"The trust established between China and the ASEAN countries is highly precious, and the stabilized situation in the South China Sea was earned by hard work," Hua said.

China hopes to continue working with all related parties to fully and effectively implement the spirit of the Declaration of Conduct in the South China Sea, promote negotiations toward a code of conduct in the region and enhance maritime cooperation, the spokeswoman said.

Ryacudu made the remarks days before US Defense Secretary Jim Mattis began a one-week trip to Asia on Sunday, hoping to strengthen defense cooperation with Indonesia and Vietnam, both of which he will visit.

Mattis is to meet on Tuesday with Indonesian President Joko Widodo and Ryacudu in the capital Jakarta for talks on maritime cooperation.

Mattis' visit comes shortly after the US released the summary of its 2018 National Defense Strategy, in which it called China "a strategic competitor using predatory economics to intimidate its neighbors while militarizing features in the South China Sea".

On Wednesday, US guided missile destroyer USS Hopper entered waters within 12 nautical miles off Huangyan Island before the Chinese Navy warned it to leave.

Teng Jianqun, director of the Department of American Studies at the China Institute of International Studies, said recent US remarks on China show that the country is still employing "Cold War thinking and zero-sum game theory".

"The US has forgotten that the world has entered a multipolar system and promoting global cooperation rather than political competition is the new trend," Teng said.

AFP contributed to this story.