Chinese police have arrested a man in connection with a series of package bombs set off at public buildings that killed at least seven people and injured another 51 in southern China's Guangxi province.

The bombs were detonated between 1:15pm and 5:00pm local time in the city of Liuzhou on Wednesday, state media reports said. 

The official Xinhua news agency said police had determined the blasts were a "criminal" act and identified the suspect as a 33-year-old local man surnamed Wei, but added the investigation was continuing.

Media images showed a collapsed building, smoke and streets strewn with rubble in Liuzhou in Guangxi region. Two people were missing, state radio said on its microblog.

Bombs were sent to 15 places ranging from hospitals and shopping malls to prisons and government offices, reports said, adding that a "terrorist" attack had been ruled out.

The Ministry of Public Security has sent criminal investigators to the scene.

Explosives and small bombs are regularly used in response to personal or professional disputes in some parts of China in what state media often refer to as revenge attacks.

Guangxi sits on the border with Vietnam and has several ethnic minorities, but is generally calm.

Such "sudden incidents", as Chinese authorities refer to them, are sometimes seen as linked to a widening gap between rich and poor and anger at corruption or environmental problems.

Hundreds have died in recent years in China's far western region of Xinjiang, in violence blamed by the government on Islamist groups, but that unrest only occasionally spills over into other parts of the country.

Source: Agencies