Chinese President Xi Jinping is understood to have made a surprise visit to the northeastern Chinese port city of Dalian, meeting a “special guest” from North Korea. Xi would also use the trip to Liaoning province to oversee the first sea trial of China’s first domestically built aircraft carrier, two independent sources told the South China Morning Post. The identity of the North Korean guest has not been officially confirmed but preparations on the Chinese side suggest the representative is a high-level official.

A source said an aircraft carrying high-ranking North Korean officials had landed in the city. The meeting comes ahead of a summit between US President Donald Trump and North Korean leader Kim Jong-un later this month or in early June. Kim visited Beijing in March on his first international trip, a gesture that signalled China was still a player in the Korean peninsula denuclearisation process.

Earlier reports said that in return Xi planned to visit Pyongyang, possibly in June. Videos posted online showed at least four Chinese Red Flag luxury sedans arriving in Dalian on Monday, indicating that a top leader from Beijing was in the provincial city. One source said Xi was expected to officiate at the launch of the aircraft carrier’s sea trials.

“The Type 001A [carrier] will have a formal sea trial ceremony, probably today or tomorrow. President Xi will need to attend because it’s the first aircraft carrier that has been 100 per cent developed and built by Chinese shipbuilders,” the source said. “Preliminary tests for the Type 001A carrier’s sea trial began last month, but the formal ceremony could not take place until Xi was available to come.”

The first source also said Xi’s presence would signal the roll-out of regulations demanding formal launches for new military weapons to boost morale. “The People’s Liberation Army needs to rebuild its spirit by creating new traditions,” the source said.

The Liaoning Maritime Safety Administration had announced on Friday that a sea area outside the Dalian shipyard where the Type 001A carrier was built would be cordoned off for military activity for one week. A second source told the Post that the shipbuilders were testing all parts of the vessel’s structure.

“To ensure the maiden sea trial goes smoothly, the Type 001A has been put through a series of tests in the past weeks, including tests on its communications, propulsion, radar, navigation and damage control systems,” the source said.

A main engine run was conducted on April 17 and again on April 23, according to Beijing-based military expert Zhou Chenming. The Type 001A’s propulsion system uses eight steam turbines – a design copied from the Soviet TB-12 engines used by its sister ship, the Liaoning, which is a refitted Soviet-era Admiral Kuznetsov-class aircraft carrier.

On Saturday, an advanced Z-18 transport helicopter took off from the deck of the new carrier, flying for about five minutes before returning to land on the vessel, testing its ability to move troops and weapons in an emergency.