Xi will meet with North Korean leader Kim Jong Un during the latter's upcoming state visit to Pyongyang to discuss bilateral relations, as well as the situation on the Korean peninsula, according to the International Liaison Department Head of the Communist Party of China Central Committee, Song Tao, at a Tuesday news conference.
North Korea has yet to comment on the fishermen.
"While the relationship between China and North Korea is no longer as close as 'lips and teeth, ' as it used to be portrayed, Xi Jinping will want to demonstrate that he is still the key global player when it comes to dealing with North Korea, and that China can not be sidelined in any future negotiations on the country's nuclear program", Katie Stallard-Blanchette, a fellow with the Wilson Center think tank in Washington, wrote in a blog post Tuesday.
Analysts say that Xi's journey is intended as a signal to Trump of his influence and backing for Kim.
Kim also wants to strengthen his own position against Trump and is obviously seeking to cement China, the North's only major ally and economic lifeline, as a major player in the process.
Chinese President Xi Jinping has written a rare opinion piece in North Korea's official newspaper Wednesday, just a day before his scheduled visit to Pyongyang, saying Beijing's friendship with the isolated North is "irreplaceable".
Seoul's Unification Ministry said the two other fishermen were sent back to North Korea through an inter-Korean village.
Chinese President Xi Jinping is to visit North Korea on Thursday and Friday.
The visit comes as nuclear negotiations between Kim and US President Donald Trump have soured after a second summit in February broke up without a deal, failing to agree on what Pyongyang would be willing to give up in exchange for sanctions relief.
The trip, his first since assuming office in 2013, will also mark the first time in 14 years that a Chinese leader has visited the North and comes on the heels of four visits to China by Kim since last year.
Kim during his summits with Trump and Moon signed vague statements on a nuclear-free Korean Peninsula, but the North for decades has pushed a concept of denuclearization that bears no resemblance to the American definition, vowing to pursue nuclear development until the United States removes its troops and the nuclear umbrella defending South Korea and Japan. During previous periods of tension, Beijing has called for "dual suspension" of the North's nuclear and missile activities and of the large-scale military exercises between the USA and South Korea.