Another good sign was that the summit lasted one hour longer than scheduled as the two sides made joint efforts to restore trust, the official said.

During the summit, Moon and Xi agreed on four basic principles in dealing with North Korea's nuclear threat: No war on the Korean Peninsula, denuclearization of the peninsula, peaceful resolution of the nuclear issue and improvement in inter-Korean relations.

The official said that the principles do not conflict with the US position.

"Military options are to back up diplomatic and peaceful means," the official said. "Peaceful and diplomatic resolution is the official US position and I believe the agreement on the four major principles is not different from the US position."

With regard to Chinese security guards' beating of South Korean photojournalists, the official said that Foreign Minister Kang Kyung-wha expressed "strong regret" to Chinese Foreign Minister Wang Yi.

"I wish the injured journalists have a quick recovery," the official said. "Something that can't happen has happened."

Moon also directed his top security advisor Chung Eui-yong to pay a visit to the journalists and take necessary measures, the official said.

"I think we can talk about follow-up measures after finding out how this happened," the official said.

The violence happened Thursday ahead of the summit when the Chinese guards blocked Korean photographers from following Moon visiting various booths at a trade fair in Beijing involving hundreds of South Korean firms and prospective Chinese buyers.

As the journalists protested the blockage, security guards took one of them outside of the venue and beat him up despite strong protests from his colleagues and South Korean officials, including those from the presidential office Cheong Wa Dae.

He was taken to a hospital after Moon's medical staff examined him and said he required intensive treatment. Another photojournalist was also injured in an earlier incident where he was pushed back by a different group of security guards at the same venue.

Some Korean media have also raised criticism of the Chinese foreign minister for tapping Moon on the arm, saying it could be considered a diplomatic gaffe. But the official said Wang made the gesture as Moon expressed friendliness toward him first.

"I hope this will be taken as meaning that (the two) have become this close," the official said. (Yonhap)