In its assessment of the demonstration, the Congolese National Police (PNC) said the 20 included individuals who allegedly vandalised the Kianza police station.

"Three police officers were arrested as a result of the brutality inflicted on the demonstrators and on a minor," Actualite CD website reported.

Police said at least 27 law enforcement forces were injured, three of whom were in serious condition.

A journalist was also beaten up "by a gang of overexcited protesters", Actualite CD said.

Earlier reports said that 23 police officers and 14 civilians were injured during the violence.

The demonstrations were organised by four opposition parties to protest against the high cost of living, widespread insecurity in the eastern part of the country and the lack of transparency in the preparations for elections scheduled for December.