A leading international rights group has accused Mozambique's security forces of a brutal, three-month crackdown on protests after the country's election last year.

Mozambique’s main opposition leader has returned from self-imposed exile as security forces fired tear gas at hundreds of his supporters who gathered near the main international airport to welcome him home.

Violence that engulfed Mozambique after the country’s highest court confirmed ruling party presidential candidate Daniel Chapo as the winner of disputed Oct. 9 elections has killed at least 21 people, including two police officers.

Rights and civil society groups say more than 100 people including children have been killed by security forces in post-election protests in Mozambique that have lasted nearly two months.

Two medical groups in Mozambique say at least 10 people were fatally shot by police and 63 others sustained gunshot wounds when authorities cracked down on unrest following the presidential election.

Mozambicans are expected to turn out in large numbers on Wednesday for an election that will choose a successor to President Filipe Nyusi after his two terms.