Mozambique's opposition on Friday promised fresh protests, as rights groups said at least 30 people had been killed in three weeks of demonstrations over contested election results.

The southern African nation has been rocked by violence since the Frelimo party was announced winner of the October 9 elections with more than 70 percent of votes. The party has been in power for almost 50 years.

Opposition leader Venancio Mondlane, who won 20 percent of the vote according to the election authority, claims the vote was rigged. In social media posts, he has called his supporters onto the streets in protest. In the biggest demonstration yet, thousands of opposition supporters marched through Maputo on Thursday.

Human Rights Watch did not have a toll for Thursday’s protests but said it had counted at least 30 dead between October 19 and November 6 across the country. This includes two opposition figures shot dead on October 19. Mozambique’s Centre for Democracy and Human Rights (CDD) said at least 34 were killed, according to its tally.