A North Korean delegation arrived in Beijing on Monday, Japanese media said, as the two allies step up diplomatic contacts ahead of a landmark meeting between Kim Jong Un and Donald Trump.
Japanese broadcaster NHK showed images of officials leaving the VIP area of the Chinese capital's airport.
The broadcaster said later the group had arrived at the Diaoyutai government guest house although the identity of the visitors was not immediately known.
The report comes a week after Kim made his second trip to China in less than two months to again meet with President Xi Jinping.
Kim's latest visit was to the northeastern port city of Dalian, as the two countries seek to mend frayed ties with a diplomatic thaw in the region gathering pace.
Relations fell to a new low in the past year as Beijing, angered by Pyongyang's nuclear and missile tests, backed a series of United Nations sanctions against its Cold War-era ally.
But Beijing is keen to avoid being sidelined in the wake of Kim's historic summit last month with South Korean President Moon Jae-in and ahead of his upcoming meeting with Trump in Singapore on June 12.
Experts say Kim also needs to maintain good relations with his country's main patron to back him up as the Trump summit looms.
Kim, who picked Beijing to make his maiden official trip abroad in March, has also invited Xi to visit North Korea.
The latest visit by a North Korean delegation comes after Kim Jong Un made two trips over the border to see Xi Jinping