Chinese President Xi Jinping and US President Donald Trump will discuss whatever they want when they meet at the G20 summit in Japan, China's foreign ministry said on Wednesday.

Ministry spokesman Lu Kang also told a regular news briefing that an agreement between China and the United States on trade was not only in the interest of the two countries, but also meets the aspirations of the world.

Four decades of dealings between China and the United States show that positive outcomes were always possible, China's foreign ministry said after their presidents agreed to rekindle trade talks at a G20 meeting this month.

US President Donald Trump said on Tuesday he would meet Chinese President Xi Jinping at the G20 summit in Osaka, Japan. China, which previously declined to say whether the two leaders would get together, confirmed the meeting.

The world's two largest economies are in the middle of a costly trade dispute that has pressured financial markets and damaged the global economy.

Talks to reach a broad deal broke down last month after US officials accused China of backing away from agreed commitments. Interaction since then has been limited, and Trump has threatened to slap more tariffs on Chinese products in an escalation that businesses in both countries want to avoid.

In another potential sign of a pre-G20 thaw, state television's movie channel, which has in recent weeks broadcast old patriotic films about China's heroics against the United States in the 1950-53 Korean War, on Wednesday showed a movie that put the United States in a far more positive light.

The channel showed 1999's “Lover's Grief over the Yellow River”, about a US pilot in World War Two who is rescued by Communist guerrilla forces in China and falls in love with one of the young women fighters.