Officials say Xi Jinping briefed Donald Trump on the sidelines of the G20 summit in Osaka. (File)

Chinese President Xi Jinping urged US President Donald Trump to ease sanctions on North Korea during their meeting in Japan last month, China's Foreign Ministry said on Friday.

China has signed up for strict UN sanctions following North Korea's repeated missile and nuclear tests but has also suggested sanctions could be eased to reward North Korea for good behaviour.

Chinese Foreign Ministry spokesman Geng Shuang told reporters that Xi briefed Trump on China's position on North Korea when they met on the sidelines of the G20 summit in Osaka.

"In the meeting with President Trump in Osaka, President Xi briefed him on China's principled position on the peninsula issue, and pushed the U.S. side to show flexibility and meet the North Koreans half way, including easing sanctions in due course," Geng said.

Xi and Trump have both held talks with North Korean leader Kim Jong Un recently - Xi before the G20 summit during a trip to Pyongyang, and Trump after the summit, when he met Kim at the Demilitarised Zone along the North's border with South Korea.

The United States hopes to see a freeze in the North Korean nuclear programme as the start of a process of denuclearisation, the State Department said on Tuesday, ahead of fresh talks with Pyongyang supposed to take place this month.