Japan plans to help prevent the theft of precious artifacts from being stolen from the ruins of Sumer in southern Iraq, site of the world's oldest known city-state system, government sources said.

Because valuable artifacts continue to disappear from the ruins, Japan will help local authorities tighten security at the sites, providing them with patrol vehicles and other equipment, according to the sources.

The government is considering extending such assistance to Iraq through UNESCO, using $600,000 in grant aid, the sources said.