A prison riot in Mozambique's capital Maputo left 33 people dead and 15 injured, the country's police general commander Bernardino Rafael said on Wednesday, as civil unrest linked to October's disputed election continues.

A decision on Monday by Mozambique's top court confirming long-ruling party Frelimo's victory in the election has sparked fresh nationwide protests by opposition groups and their supporters who say the vote was rigged.

While Rafael blamed protests outside the prison for encouraging the riot, Justice Minister Helena Kida told local private broadcaster Miramar TV that the unrest started inside the prison and had nothing to do with protests outside.

"The confrontations after that resulted in 33 deaths and 15 injured in the vicinity of the jail," Rafael told a media briefing.

The identities of those killed and injured were unclear.

About 1,534 people escaped from the prison in the incident but 150 have now been recaptured, Rafael said, adding that there were prison break attempts at two other prisons.

"We are worried as a country, Mozambicans and security forces," Rafael said. "We expect in the next 48 hours a rise in crime."

Mozambique's interior minister said on Tuesday that at least 21 people were killed in unrest after the top court's decision.

Prior to Tuesday, civil society monitoring group Plataforma Decide said at least 130 people have been killed in clashes with police since the unrest started.