Twenty-one of the sixty Japanese bombs unearthed on Thursday in Ning'an City, northeast China's Heilongjiang Province, have been confirmed to contain deadly chemicals.

No chemicals have leaked from the bombs, sources with the office in charge of abandoned weapons at the Chinese Foreign Ministry said Friday.

Experts from China and Japan began on Wednesday excavating the pit at the Ning'an Chemical and Light Industry Company were they expected to recover about 200 bombs.