LANZHOU - Five people were killed in a coal mine accident that was kept under wraps up for over 40 days in Northwest China's Gansu province, local authorities said Sunday.

The government of Shandan county launched an investigation after receiving a public tip that the Jinwan coal mine had covered up an accident that killed five miners, the government's information office said in a statement issued on Sunday.

The coal mine was operating illegally, as it had been previously shut down for renovations, according to the statement.

The statement said that the accident occurred on July 2, but failed to mention how the miners died. However, a report on the website of the People's Daily newspaper quoted a local resident as saying that they were killed in a gas explosion.

The coal mine silenced the relatives of the dead with compensation payments, the statement said.

Mine owner Zhao Erfeng, who is now in police custody, confessed to the cover-up during an investigation by local authorities, it said.

Police are still looking for Huang Chao, deputy manager of the mine, the statement said.