Chinese President Xi Jinping on Friday called on leaders of the Asia-Pacific region to strengthen multilateralism and openness in his first public speech after meeting with US President Donald Trump a day earlier.

Speaking at the opening of the Asia-Pacific Economic Cooperation (APEC) summit in Gyeongju, South Korea, Xi called on countries to "work together" in the face of global uncertainty and support the World Trade Organization-led trading system.

"We must adhere to the right direction of WTO reform, defend fundamental principles such as most-favored-nation treatment and non—discrimination, and contribute to the modernization of international trade and economic rules," the message says.

He said China will continue to open up its economy and "join forces" to ensure stable supply chains, rather than "breaking chains."

Xi's comments came a day after his important meeting with Trump in Busan, where the leaders discussed trade and agreed on key issues to finalize the details soon.

The talks, which Trump described as "very successful," included a tentative agreement to reduce some tariffs and resume key agricultural imports, but did not provide concrete steps to do so.

Without directly mentioning the United States, Xi promised that China would "open up more to the world" and implement reforms in accordance with the high standards of global trade rules.

He also stressed the importance of cooperation in the field of digital commerce, green industries and inclusive development throughout the region.