Japanese officials are beginning excavations in Tokyo which they believe could reveal grisly secrets from World War II.

Officials are at the site of a former army medical school which carried out experiments on prisoners.

Japan's government ordered the excavation after a former nurse came forward, breaking 60 years of silence.

The woman, now 88, said she and her colleagues were ordered to bury hundreds of bodies, many in pieces, after Japan's surrender at the end of the war.

The site - from which an apartment block is being cleared for the digging - was the Tokyo headquarters of Unit 731 of Japan's Imperial Army.

Historians and witnesses say it subjected many thousands of prisoners in occupied northern China to barbaric experiments, searching for advances in biological warfare.

- BBC