Chinese President Xi Jinping on Monday expressed concerns over rising tension between North Korea and the United States, calling for them to maintain the momentum for dialogue, South Korea's presidential office said.

"There are many people concerned about the tense situation on the Korean peninsula," Xi told South Korean President Moon Jae-in during a summit in Beijing, according to Moon's spokeswoman Ko Min-jung.

"China and South Korea should gather strength to help North Korea and the United States sustain the momentum for dialogue."