Police in Democratic Republic of Congo fired shots in the air on Tuesday to halt a second day of protests against a draft measure that could delay a presidential election set for 2016 and allow President Joseph Kabila to stay in power.
Kabila won elections in 2006 and 2011 and is constitutionally ineligible to stand for a third term.
Students burned tires and barricaded the road leading to the University of Kinshasa in the south of the capital and large numbers of people were in streets in the Ndjili neighborhood, blocking access to the airport, witnesses said.
Riot police deployed across the city but protests appeared to be less organized and more sporadic than on Monday, when at least four people died in clashes.
The Senate began to examine a revision to the electoral code that would require a census before the 2016 election. Critics say any census would take at least four years and is a ploy to extend Kabila's tenure beyond the end of his mandate.
Congo's economy has long been crippled by mismanagement, corruption and two decades of armed conflict in the country's eastern borderlands. But investors have long been attracted to its largely undeveloped mineral reserves.
SMS service for mobile phones, Wi-Fi and mobile internet were all down in Kinshasa and the eastern city of Goma on Tuesday, witnesses said.
A diplomat in the capital said the government had ordered the service shut throughout the country. The reasons were not clear and there was no immediate comment from the government.
France's foreign ministry said unrest of the type seen on Monday in Congo had no place in democratic debate and it was essential that the electoral calendar be agreed in a consensual fashion respecting the constitution and public liberties.
In another sign of political tension, opposition leader Jean-Claude Muyambo was detained by armed men in hoods at his residence in Kinshasa, said Vital Kamerhe, president of the opposition Union for the Congolese Nation (UNC) party.
Muyambo defected last November from Kabila's ruling coalition. Government spokesman Lambert Mende said his arrest was ordered by the public prosecutor's office after a complaint about a real estate sale and had "no link to political issues."