Police in Democratic Republic of Congo dispersed opposition protests in several cities on Tuesday against proposed constitutional changes that critics say could allow President Felix Tshisekedi to seek a third term, with Reuters witnesses reporting tear gas and warning shots in Kinshasa.

The demonstrations were called by the opposition C64 coalition, linked to former presidential candidates Martin Fayulu, Moise Katumbi and Delly Sesanga. A previous protest organised by C64 in the capital Kinshasa in June was violently dispersed by security forces.

Several hundred people took part in the protest in Kinshasa, according to two Reuters witnesses. In the cities of Lubumbashi and Uvira, protests were officially prohibited by local authorities but went ahead anyway and were quickly dispersed, two other witnesses said.

The protest in Kinshasa was authorised and began peacefully, but clashes broke out between protesters and pro-government supporters. Both sides threw stones and brandished machetes, prompting the police intervention, two Reuters witnesses said.

The protests come three weeks after Tshisekedi announced plans for a national dialogue bringing together opposition parties, civil society groups and religious leaders, but excluding rebels who control parts of eastern Congo.

He has presented the dialogue as a way to address the country's political challenges. Opposition parties and the powerful Catholic Church have condemned proposed constitutional changes that could allow Tshisekedi to seek a third term.

Congo's constitution limits presidents to two five-year terms. Parliament adopted a bill in June allowing constitutional changes to be put to a referendum, and members of Tshisekedi's coalition have backed changes that would allow him to remain in office.