Xi visited North Korea prior to meeting Trump at the G20 in Japan on Saturday, and analysts had said the Chinese leader could use the trip as leverage in his trade war talks with the US leader.

Trump met North Korean leader Kim Jong Un the next day at the Demilitarized Zone dividing North and South Korea.

Chinese Foreign Minister Wang Yi told reporters on Tuesday that Xi "pushed for the US to show flexibility and meet the DPRK (North Korea) halfway, including the timely easing of sanctions against the DPRK and finding a solution to each other's concerns through dialogue."

China and North Korea have worked to improve relations in the past year after they deteriorated as Beijing backed a series of UN sanctions against its Cold War-era ally over its nuclear activities.

But Beijing has sought to keep Pyongyang within its sphere of influence and Kim met Xi four times in China in the past four years.

A week before the G20 summit in Osaka, Xi became the first Chinese leader to visit North Korea in 14 years in a trip analysts said was meant to showcase China's influence over the North prior to trade talks with the US.

After his impromptu stop on North Korean soil over the weekend, Trump said he and North Korean leader Kim Jong Un agreed to start working-level talks on a denuclearisation deal, ending a standstill in place since the two leaders' second summit, in Hanoi in late February, ended without an agreement.