North Korean leader Kim Jong Un has arrived in China's border city of Dandong via a new bridge linking the two countries, South Korea's Yonhap News Agency reported Saturday, citing a government source.

The report said Kim crossed the New Yalu River Bridge, which opened last week, 12 years after its completion, amid a marked improvement in ties.

Prompting speculation for a visit by a high-level North Korean figure, strict traffic restrictions had been imposed in parts of Dandong, diplomatic sources said. Hotel rooms in the area were unavailable for booking.

China will mark the 76th anniversary of the Chinese People's Volunteer Army's entry into the Korean War on Sunday.

China and North Korea held a ceremony on Oct. 15 to inaugurate the bridge connecting Dandong with Sinuiju, on the North Korean side of the Yalu River. It is expected to boost trade and personnel exchanges between the neighboring countries.

China's Xinhua News Agency reported on the opening day that Chinese Premier Li Qiang, in a video message to the ceremony, described the new bridge as an "important cross-border infrastructure project" backed by Chinese President Xi Jinping and the North Korean leader.

The two countries have been strengthening their ties since Kim visited Beijing in September last year to attend events marking the 80th anniversary of Japan's surrender in World War II and met with Xi for the first time in more than six years.

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