China's postal service is ordering tighter checks on packages following a series of mail bombings that killed 10 people and injured 51.

The State Post Bureau said on its website Saturday that mail carriers and overnight delivery services would be required to conduct further checks for explosives, dangerous chemicals, weapons, gunpowder and poisons. Closer cooperation with police will also be required.

The order follows a series of 18 explosions in the southern region of Guangxi on Wednesday and Thursday blamed on a 33-year-old man, Wei Yinyong, who had long-standing disputes with neighbors and companies involved in stone quarrying.

The explosions hit a hospital, markets, a shopping mall, a bus station and several government buildings. Wei was believed to have been killed in one of the blasts.