BEIJING: North Korean leader Kim Jong Un arrived on Tuesday on an unannounced visit to Beijing for talks with President Xi Jinping, as preparations ramp up for an expected second summit with Donald Trump.

China is the key ally of isolated, nuclear-armed North Korea and its main source of trade and aid.

After arriving in the Chinese capital, Kim met Xi for around an hour, Seoul`s Yonhap news agency reported on Tuesday, citing unnamed sources who said the talks focused on a possible summit with US President Trump and ways to deepen ties.

Kim and his wife Ri Sol Ju then attended a dinner hosted by Xi and first lady Peng Liyuan at Beijing`s Great Hall of the People, Yonhap reported.

China`s foreign ministry earlier said Kim would meet Chinese leaders to discuss `relevant issues` but did not reveal more about his itinerary.

The North Korean leader, accompanied by several senior officials, had left Pyongyang on his private trainonMonday,the official Korean Central News Agency reported.

The trip, at Xi`s invitation, is set to run until Thursday, according to KCNA and China`s official Xinhua news agency.

Kim`s fourth visit to China comes a week after he warned in a New Year`s speech that Pyongyang may change its approach to nuclear talks if Washington persists with sanctions.

`Both Xi and Kim see value in coordinating their positions in advance of Trump-Kim summits. That appears to be a pattern, Bonnie Glaser, a senior adviser at the Center for Strategic and International Studies, told AFP.

`Kim also seeks Beijing`s help in getting international sanctions eased.` While China and Russia have both said the United Nations should consider relaxing sanctions on Pyongyang, Trump insisted on Sunday that they would remain `in full force` until the US sees `very positive` results on the nuclear issue.

Kim`s trip coincides with the second day of talks between US and Chinese officials in Beijing aimed at resolving their trade war, but China rejected the notion that it was using the North Korean issue as a bargaining chipin the negotiations.

`Xi also gains from a summit with Kim and the timing could not be any better,` said Harry Kazianis, director of defence studies at the Center for the National Interest, a US think tank.

`With Chinese and US officials meeting to discuss how to end the growing trade war between the two superpowers, it shows Beijing clearly has a North Korea card to play if it sees fit.` The trip began under the usual veil of secrecy and Kim has not been spotted in public since a motorcade believed to be carrying the North Korean entourage left a Beijing train station under heavy security early on Tuesday.-AFP