Donald Trump has called on North Korea to “make a deal” on the eve of a visit to China where Pyongyang’s military build-up and trade will be on the agenda.

In a shift from his usually combative tone towards the rogue state, Mr Trump said diplomacy could be an option in dealing with the North’s military provocations.

"It makes sense for North Korea to come to the table and make a deal that is good for the people of North Korea and for the world," Mr Trump said, at a joint press conference with Moon Jae-in, the South Korean president, in Seoul.

Mr Trump also praised Xi Jinping, the Chinese president, for being “very helpful” on the North Korea issue and appeared to indicate that China could unveil fresh measures to confront Pyongyang, saying: "We'll find out how helpful soon.”

The US president will arrive in Beijing on Wednesday for what could be the trickiest leg of his mammoth five-nation Asian tour.

He wants to press Chinese leaders on what he considers to be ‘unfair’ trading practices, but is also seeking tougher action from China in reining in North Korea’s nuclear programme.

China has traditionally been the North’s only diplomatic ally and a key trading partner.