By Wednesday, 589 rescue workers had been mobilized nationwide to help save the miners, and more than 390 machines were working at the site.

Two senior officials in Qixia have been removed from their posts for the late reporting of the explosion, which delayed rescue work.

An investigation has also been launched to determine the cause of the blast.

Chen, the mayor, said anyone found responsible for the accident would "not be spared".

Liu Jiayi, Party chief of Shandong, and Li Ganjie, the provincial governor, have visited the site several times.

They urged the rescuers to spare no effort and use every minute to save those trapped.