Relations between Beijing and Seoul have been icy since South Korea allowed the United States to install a defence system to guard against missile threats from North Korea.
The presidents of China and South Korea sought Thursday to repair relations strained over a US anti-missile defence system, but the the incident of Chinese security beating a South Korean photojournalist has cast a pall over the summit.
Relations between Beijing and Seoul have been icy since South Korea allowed the United States to install the THAAD (Terminal High Altitude Area Defense) system to guard against threats from North Korea.
China considers THAAD a threat to its own security, and has imposed economic measures against South Korean companies in a move seen as retaliation.
South Korean President Moon Jae-In and Chinese leader Xi Jinping signalled their willingness to improve relations as they met at the Great Hall of the People in Beijing.
Xi said Moon's first state visit to Beijing was an "important opportunity to improve relations as we seek to find ways to carve a better path based on mutual respect and trust."
The Chinese president said he was willing to "step up" communication and co-ordination with Moon, stating that "we shall deepen the connection and accurately navigate the bilateral relationship."
He added the two countries could also support each other and increase co-operation as they prepared for their respective Winter Olympic games, to be hosted in Pyeongchang next year and in Beijing in 2022.
Moon praised Xi, calling him a "very sincere and reliable leader in terms of both words and behaviour."
China and South Korea were "partners set by destiny to walk the path of mutual prosperity and co-operate for world peace," he said, while acknowledging the recent "temporary difficulties."
North Korea talks?
Improving Sino-Korean ties has become increasingly important amid growing concern that bellicose rhetoric between Washington and Pyongyang could spark war on the Korean peninsula.
The two leaders met amid mixed US signals that Washington is willing to hold talks with Pyongyang.
"As friendly neighbours and strategic partners, China and South Korea have broad common interests in keeping the region peaceful," Xi said.
Moon noted that he expected to "reaffirm and discuss specific co-operation" with Xi on the issue.
Their meeting came after US Secretary of State Rex Tillerson said Washington was ready to talk to North Korea "without preconditions", though it was determined to force Pyongyang to give up its nuclear arsenal.
China and Russia welcomed Tillerson's remarks, even after the White House appeared to put his proposal in question by saying Trump's "views on North Korea have not changed."
Hours before the summit, Chinese security personnel beat and severely injured a South Korean photojournalist covering Moon's attendance at a trade partnership event, according to the Korea Press Photographers Association (KPPA).
Security blocked South Korean photographers from following his delegation, grabbing one photographer by the neck and throwing him to the ground, then seizing another's camera, the KPPA said.
When the Chinese guards again tried to block journalists from entering another event hall—even though they showed identity cards—a photographer with the surname Lee objected to the move.
More than 15 guards surrounded him and "punched him repeatedly, before even kicking him on the face after he was knocked to the floor," leaving him with a bloody nose, a severe injury to his right eye, nausea and dizziness, the KPPA said in a statement.
South Korean officials lodged a complaint and demanded a formal apology from China, the Yonhap news agency said.
Chinese Foreign Ministry Spokesman Lu Kang voiced concern over what he said he hoped was "just a minor incident".
Both countries had made "meticulous preparations" for Moon's trip "with the same goal in mind, which is that we want to make sure that this visit is very successful," Lu told a regular press briefing.