Members of Zimbabwe's defeated opposition party were due to appear in court Saturday, accused of involvement in the deadly violence that followed this week's historic elections.The appearance by 24 people arrested in a police raid at opposition MDC headquarters comes a day after President Emmerson Mnangagwa was declared the winner of a vote which his rival Nelson Chamisa says was rigged.Zimbabwe Lawyers for Human Rights, a non-profit group, said the opposition members were charged with "committing public violence" during Wednesday's protests in Harare.At least six people died after troops opened fire on demonstrators alleging that Mnangagwa had stolen Monday's election from Chamisa.The crackdown sparked an international outcry, raising grim memories of the violence that marred polls under autocrat Robert Mugabe who was ousted last year after 37 years of iron-fisted rule. Mnangagwa has accused the opposition of fomenting the unrest, but said on Friday that he would set up an independent commission to investigate the killings."No democratic process is flawless," Mnangagwa said, but he insisted the election was "free, fair and credible", a far cry from the fraud-tainted polls of the Mugabe era.He also called for unity, telling Chamisa: "You have a crucial role to play in Zimbabwe's present and in its unfolding future."Court challenge Chamisa, a 40-year-old pastor and lawyer, has urged his supporters to refrain from violence as he prepares to challenge the results in court."We won but they declared the opposite. You voted but they cheated," he said on Twitter on Saturday. Mnangagwa, 75, has said Chamisa is free to mount a legal challenge, though such a move appears to have little chance of success in changing the results.Mnangagwa won 50.8% against Chamisa's 44.3%, according to the Zimbabwe Election Commission - just scraping over the 50% threshold needed to avoid a second run-off round.Paul Mangwana, a spokesperson for the ruling Zanu-PF party, said the courts would have 14 days to consider any legal challenge, after which the winner would be inaugurated within two days.Fresh start for Zimbabwe? A former right-hand man to Mugabe, Mnangagwa was chosen to lead Zanu-PF after the brief military intervention last November that ousted the veteran leader.Mnangagwa was allegedly involved in state violence during the 2008 elections when the opposition pulled out of the run-off, following the deaths of at least 200 supporters in attacks.Mnangagwa has hailed the first post-Mugabe polls as a "new beginning" and pledged to represent all Zimbabweans, including those who did not vote for him.But rights groups have expressed concern that heavy-handed policing to prevent more post-election protests indicate how he intends to govern.Amnesty International said more than 60 people had been "arbitrarily arrested" in a post-election clampdown on the opposition."President Mnangagwa must make good on his commitment to settling political differences peacefully, respectfully, and within the confines of the law," said Amnesty's southern Africa director Deprose Muchena.Seeking to end Zimbabwe's international isolation, Mnangagwa has made a priority of attracting badly needed foreign investment.He pronounced the country "open for business" on Friday, adding: "We want to leapfrog and catch up with other developing countries."Mugabe, who had ruled since independence from Britain in 1980, left Zimbabwe's economy in tatters, presiding over the seizure of white-owned farms and hyperinflation.* To follow the latest on the Zimbabwe elections SIGN UP TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook. Health and education services, once strong, are in ruins, while millions of people have fled abroad to seek work. President Cyril Ramaphosa of neighbouring South Africa was the first key partner to congratulate Mnangagwa, calling on all Zimbabweans to accept the result. The United States, meanwhile, urged Mnangagwa to show "magnanimity" and the opposition to show "graciousness in defeat".International observers have largely praised the conduct on election day itself, when Zanu-PF also won a large majority in parliamentary elections.EU monitors have however said that Mnangagwa, who enjoyed tacit military support and control of state resources, benefited from an "un-level playing field".The Zimbabwe Election Support Network, a non-partisan observer group, estimated Chamisa could have won up to 47.8% of the vote based on its monitoring work.