Police have published the online chat logs and diary of the bomber responsible for a government office blast that killed four people and injured 16 others in southwest China's Yunnan province last Thursday.

Zhao Dengyong, a 26-year-old male from Baogunao township in Qiaojia county, detonated explosives at a housing demolition office in the city of Zhaotong around 9 a.m. on May 10, a county police spokesman said the following evening.

"This cruel society is driving me crazy. I don't know how many people will be killed by me when I can't go on with my life," Zhao wrote to an unknown correspondent via QQ, a popular instant messaging program.

"I have nothing, except for my healthy body. Those bastards believe that money talks. Don't they know that if I can't live, they can't either?" Zhao wrote in his online diary.

Qiaojia county police released Zhao's diary entries and chat logs on Monday. Based on the evidence released, as well as interviews with local residents and surveillance video footage of the bombing, police believe that Zhao's motivation was not derived purely from his anger with the housing demolition office, but also from his hatred for society.

The explosion killed Zhao, two local residents and an official at the scene.

Four people who were severely injured were rushed to a hospital in the provincial capital of Kunming, while 12 others with lighter injuries are being treated at a local hospital.