North Korea and China on Saturday kicked off a 40-day repair work on a railroad bridge that links the two countries' border cities, a source familiar with the matter said.

The source said that the countries started maintenance work on the railway system on the bridge linking North Korea's border city of Sinuiju to China's city of Dandong over the Yalu River.

"During the repair period, not only trains but also vehicles will not be allowed to cross the bridge," the source said.

The bridge, built in 1943, is called the China?North Korea Friendship Bridge, serving as a main gateway between the two countries. Road and rail traffic is allowed, but people cannot cross the bridge.

Another source said that North Korea and China had been divided over how long they would go ahead with the repair work.

North Korea suggested that the renovation should be completed within 10 days, apparently out of concern that a delay in the transportation of goods will have a negative impact on the North's economy in the face of tougher international sanctions, it said.

But the source said China proposed the 40-day plan due to safety concerns.

China is expected to provide money needed for the repair works while North Korea will conduct the repairs.

China completed the construction of a new 3-kilometer bridge linking the two cities in October 2014 by injecting 2.2 billion yuan (US$330 million) into it.

But opening the bridge, located some 8 km away from the China-North Korea Friendship Bridge, has been "indefinitely" postponed as North Korea has yet to build approach ramps and connecting roads. (Yonhap)