BEIJING, April 10 (UPI) -- China pledged Wednesday to complete a survey of its internal borders within five years to curb an escalating number of violent clashes over dwindling land and natural resources.

At a ceremony Tuesday in Sichuan province presided over by the Ministry of Civil Affairs, representatives of the Tibet and Xinjiang autonomous regions marked the demarcation of 600 miles of once-contested border land, the China Daily reported.

Minister Doji Cering urged local officials to cooperate with the central government's survey, calling it "vital to the development of local economies and to regional and national social stability."

He warned of the potential for "intensified border conflicts" triggered by an increasing number of frequently bloody disputes over regional resources.

Only 5 percent of China's 65 existing boundaries delineating provinces, autonomous regions or municipalities have been designated as legal and about 20 percent are disputed by local authorities.

More than 1,000 incidents of violence involving 56,000 square miles of land have taken place, according to official statistics.

A number of feuds reported in the Chinese media erupted over mining rights and contending claims on water resources and agricultural land.

China started its national border survey in 1989 and has mapped boundaries for 18,000 miles of territory disputed among nine provinces.

The authorities want to clarify 14 provincial boundaries in northern China by the end of the year.