An explosion damaged a six-storey building in China, less than a day after more than a dozen blasts killed at least seven people and injured over 50 in the same city.

The latest blast hit a civilian's house near a highway administration bureau in Liucheng in Guangxi region, which borders Vietnam, but it was not immediately known if there were any casualties, according to the official Xinhua News Agency.

The ministry of public security said it was treating the blasts as a criminal act, and not terrorism.

It said a 33-year-old local man, identified only by his family name of Wei, was considered a suspect, but provided no further details, including a possible motive or whether the man had been detained.

Local media reported the suspect had been apprehended, and Xinhua said he had hired others to help deliver the bombs.

A local Communist Party newspaper, the Guangxi Daily, cited police as saying there were 17 explosions on Wednesday afternoon in Liucheng, leaving seven people dead, two missing and 51 injured.

The explosions hit a hospital, local markets, a shopping mall, a bus station and several government buildings, including a jail and dormitories for government workers.

Zhou Changqing, the police chief for the city of Liuzhou, which has jurisdiction over Liucheng, said the blasts were triggered by explosive devices delivered in several mail packages.

Photos posted online showed streets filled with smoke, strewn debris, dust clouds in the sky and the rubble from a five-story building that had partially collapsed.

Xinhua reported that at least one more explosion hit central Liuzhou, away from Liucheng. It did not say whether there were any casualties from that blast or whether it was connected to the ones in Liucheng.