NANJING, Jan. 28 -- The deaths in the past year of more than 40 survivors of the 1937 Nanjing Massacre have reduced the total number of living Chinese survivors of the atrocity to 133.

The official association for survivors of the massacre warned on Thursday that the number of living survivors was dwindling fast, from more than 1,000 two decades ago, with the eldest now more than 100 years old.

Japanese troops captured Nanjing on Dec. 13 of 1937. Over six weeks, they killed 300,000 Chinese civilians and soldiers who had laid down their arms, while over 20,000 women were raped.

Faced with Japanese attempts to deny the massacre, China is racing against time to preserve the survivors' testimonies, with the memorial hall to the atrocity running a project recording their accounts.

"Though traumatized, the victims have told the world the truth," said Zhu Chengshan, head of the survivors' association.

UNESCO added documents of the Nanjing Massacre to its Memory of the World Register in October.