BEIJING, May 7 -- Twelve officials are under investigation for alleged dereliction of duty or power abuse involving two mining accidents that killed 35 people in southwest China's Yunnan province in April, the Supreme People's Procuratorate said on Wednesday.

Six officials were detained for flooding at the Xiahaizi Coal Mine in Qujing City on April 7. A total of 21 miners were killed while one other remains missing.

The mine was operating illegally at the time, which involved malpractice by officials, according to the local prosecutor's investigation.

In another case, five officials were investigated for a gas explosion at the Hongtutian Coal Mine in Fuyuan County on April 21, which left 14 miners dead and caused direct economic losses of 14.98 million yuan (2.4 million U.S. dollars).

Authorities are still investigating the accidents and a suspected power-for-money deal behind the cases.