Four people have been killed in protests in the Democratic Republic of Congo over claims that President Joseph Kabila is seeking to extend his 14-year rule by delaying next year’s elections.
Protests continued on Tuesday in the capital, Kinshasa, following Monday’s fatal clashes between opposition supporters and security forces.
Protesters say government plans for a census are a ploy to delay elections.
Mr Kabila is constitutionally barred from contesting the poll.
He took power in 2001 following the assassination of his father Laurent Kabila, who was president at the time, and has won two disputed elections since then.
Police fired shots in the air to disperse protesters in Kinshasa on Tuesday, Reuters news agency reports.
Students had burned tyres and barricaded the road leading to the University of Kinshasa, it quotes witnesses as saying.
Thousands of people protested in other cities as well, including Goma, the main trading post in the east.
Government spokesman Lambert Mende said two policemen and two “looters” were killed in Monday’s clashes in Kinshasa.
Demonstrators called on Mr Kabila to step down when his term expires and carried placards which said: “Don’t touch the constitution”.
The protests coincided with a debate in the Senate over government plans to hold a census before elections.
The opposition says this amounts to a “constitutional coup” by Mr Kabila, as it will take about three years for a census to be conducted in DR Congo, which is two-thirds of the size of western Europe, has very little infrastructure and is hit by instability in the east.
DR Congo, formerly known as Zaire, has never had a reliable census since independence from Belgium in 1960.
The country is rich in resources, but most people are poor.