Chinese authorities are investigating a fresh explosion in Guangxi province, a day after a series of parcel bombs killed seven people.

The blast took place at an apartment block at 08:00 local time (00:00 GMT) in Liucheng county, said state media.

The cause was not clear, and no casualties have been reported.

Seventeen separate explosions hit Liucheng on Wednesday. Police have arrested a suspect they believe sent out the bombs in the mail.

It is unclear whether Thursday's blast is connected to the multiple blasts on Wednesday.

Thursday's fresh explosion took place at a six-storey building in a residential area. Xinhua news agency said the force of the blast had caused debris to rain down on a road opposite the building.

Local police issued a statement calling on the public to be wary of accepting parcels sent by strangers or packages "sent by non-proper channels".

The local postal service has halted all deliveries until Saturday.

The parcel bombs on Wednesday targeted a prison, a train station, a hospital and a shopping centre among other locations.

State media said besides the seven dead, another two people remained missing and 51 people were injured in afternoon's blasts.

A 33-year-old Liucheng resident, identified only by the surname Wei, is in police custody for the explosions.

The BBC's John Sudworth in Beijing says there have been a number of cases in China of disaffected people with a legal grievance against the authorities using explosive devices in public attacks.

Source: BBC