The head of the U.N. human rights agency said on Friday that Congolese security forces had killed at least 40 people and arrested 460 in protests against President Joseph Kabila this week.

“Such high casualty figures suggest a serious disregard … of the need to exercise restraint in policing demonstrations,” U.N. High Commissioner for Human Rights Zeid Ra’ad al-Hussein said in a statement.

Protests erupted against Kabila when he failed to step down despite his mandate expiring on Tuesday.

“Not only are soldiers participating in law enforcement operations, but all the forces involved are heavily armed and using live ammunition,” Zeid said, also noting that 107 more people had been “injured or ill-treated”.

Meanwhile, the country’s main opposition bloc insisted on Friday that President Joseph Kabila step aside in time for elections no later than November 2017, as a condition in an agreement being negotiated.

“For us it is essential to bring to a good conclusion this year of transition before the presidential election that must take place … in November 2017 at the latest,” Valentin Mubake, an adviser to Democratic Republic of Congo’s main opposition leader Etienne Tshisekedi, said at talks aimed at preventing the country sliding back into civil war.