HARBIN, Nov. 22 (Xinhua) -- A resident in northeast China's Heilongjiang Province has unearthed a shell believed to be from World War II, local authorities said Thursday.

The man, surnamed Zhang, found the shell when he was digging up tap water pipes at the back of his house Tuesday, and reported it to the local police.

The rusty shell measured 58 cm long and 15 cm in diameter. It has been well preserved and still poses a high risk. Police moved it to a safe place for investigation.

The police also launched a thorough check of the site to ensure the safety of local residents.

Japanese troops invaded northeast China in September 1931 and occupied the region until they surrendered in August 1945. After the Japanese retreated, large number of bombs, shells and mines were left behind. Undiscovered explosives still impose threat to local residents.