NANJING, June 21 -- Hundreds of bullets suspected of being used by Chinese soldiers in the fight against Japanese invaders during World War II have been discovered in the east China city of Nanjing.

Workers found more than 450 machine-gun bullets, cartridge cases, clips and bullet heads at a construction site outside the Memorial Hall of the Victims in the Nanjing Massacre on Friday, said Zong Ren, deputy head of the Jianye district government, where the hall is located.

Preliminary studies show that the bullets were for Soviet Union-made firearms used by Chinese soldiers during the war, Zhu Chengshan, curator of the memorial hall, told Xinhua on Saturday.

The discovery is of great importance, said Zhu.

Based on the bullets found, historical records and terrain nearby the hall, Zhu said the discovery site might have been a 1.5 meter deep trench where soldiers fought.

Further research will be carried out on the bullets.

The battle of defending Nanjing, the then capital of China, started on Dec. 1, 1937. After days of fighting, Japanese troops occupied the city on Dec. 13 and massacred over 300,000 Chinese. One third of houses in the city were burned down and more than 20,000 women were raped.

According to Zhu, excavation at the site is continuing and the area has been cordoned off. More bullets are expected to be recovered.