Zimbabwe’s opposition leader has said President Emmerson Mnangagwa’s election victory is a “coup against [the people’s] will”.
Nelson Chamisa repeated his claim that the results announced late on Thursday night were fake, and said he had won Monday’s presidential poll.
The electoral commission said “no skulduggery” was involved in the vote tally.
This was the first election since long-term leader Robert Mugabe was ousted.
Earlier, in a tweet, Mr Mnangagwa urged Zimbabweans to unite to create “a new beginning” after a vote that was intended to set Zimbabwe on a new path following years of repressive rule.
But addressing journalists on Friday afternoon, Mr Chamisa called on his rival not to accept “corrupted results”.
He also questioned the length of time it had taken to count and tally the presidential ballot.
The opposition has also expressed suspicion about the high turnout of more than 80% in most of the country’s 10 provinces.
Mr Mnangagwa took office after Mr Mugabe, 94, was forced to resign in November amid a military takeover.
What is the situation in Harare?
Riot police initially prevented the opposition MDC Alliance from holding a press conference in the capital.
The BBC’s Pumza Fihlani says police beating their riot shields chased reporters away from the venue of Mr Chamisa’s press conference.
Later an MDC Alliance lawyer said there had been a mix-up and that the police thought the opposition leader was about to address a political gathering.
Police are patrolling the streets of city after clashes between protesters and police on Wednesday left six people dead.
A police vehicle with a loudspeaker has been broadcasting the message: “Zimbabwe is open for business. We are here to protect you. Feel free to walk and open your business. All is well, fear not.”
The city, which is seen as an opposition stronghold, is quieter than normal as people are digesting the outcome, correspondents say.
But there were celebrations in one part of Harare. The president’s supporters in the suburb of Mbare took to the streets to welcome the news.
“This is a new Zimbabwe, we are happy,” AFP news agency quoted 32-year-old IT specialist Tendai Mugadzi as saying.
How close was the result?
Mr Mnangagwa avoided a run-off by just 36,464 votes out of more than 4.8 million cast.
Official results show he took 50.8% of the vote to Mr Chamisa’s 44.3%. The 21 other candidates took up the remainder.
At the last election, Mr Mugabe won 61% of the vote, with the opposition’s main candidate, the late Morgan Tsvangirai, winning 34%.
The Zimbabwe Electoral Commission (Zec) finished announcing the presidential election results in the early hours of Friday morning, after days of waiting.
Zec acknowledged that the wait had caused anxiety, and international observers had earlier urged the commission to speed up the announcement. Under the constitution, the commission had until Saturday to declare the result.
A respected Zimbabwean independent monitoring group has has added weight to the official result.
The Zimbabwe Electoral Support Network said, according to its sample survey, that Mr Mnangagwa had probably won enough support to avoid a run-off, though it left room for some doubt.
The results of the parliamentary election were announced earlier in the week. They gave Mr Mnangagwa’s Zanu-PF 144 seats; the MDC Alliance, which is made up of seven parties, 64 seats, and one seat to the National Patriotic Front, formed by Mugabe loyalists.
Although Zanu-PF won by a landslide, its majority has shrunk since the 2013 election when it obtained 160 seats and the MDC 49.
Mr Mnangagwa has vowed to revitalise Zimbabwe’s tattered economy after decades of international isolation under Mr Mugabe.
The country has suffered from rampant inflation and high levels of poverty. The unemployment rate last year was as high as 90%, according to Zimbabwe’s biggest trade union.
Bold claims face court test
Analysis by Pumza Fihlani, BBC News, Harare
It was a close finish. The “crocodile” just scraped through to legitimise his presidency, eight months after Robert Mugabe was ousted as president. But Emmerson Mnangagwa and his Zanu-PF party are not celebrating yet. Zimbabwe’s constitution allows for a legal challenge to the results but Nelson Chamisa now has the huge task of proving his bold claims.
There is no room for inflammatory talk in court – just hard evidence. Mr Chamisa has been criticised here for prematurely declaring victory and fuelling tensions particularly in the capital. If his challenge is to succeed, it won’t be through the scenes we saw on Wednesday which led to six people being killed.
Aside from the disputed results, both leaders have injected new life into their parties. They have each ignited hope for what Zimbabwe could become.
But how the next few days play out will be the true test of how ready the political leaders are to embrace true democracy – where there are winners and losers but still a country to run.
What do other countries think?
Neighbouring South Africa’s President Cyril Ramaphosa has congratulated the president on his victory, and has appealed to political leaders and the Zimbabwean people to accept the outcome of the election.
China, a key ally, endorsed the results and urged “parties to put the interest of the country and the people first and respect the choice made by the Zimbabwean people,” its foreign affairs spokesman Geng Shuang said.
European Union observers said they had found an “un-level playing field and lack of trust” in the election process.
“There were a lot of shortcomings in the campaign and [on] election day,” EU mission chief Elmar Brok told the BBC Newsday.
It was the first time in 16 years that the government had allowed EU, Commonwealth and US election monitors into the country.
Who is the president-elect?
- Emmerson Mnangagwa is known as “the crocodile” because of his political shrewdness – his Zanu-PF party faction is known as “Lacoste”
- Accused of masterminding attacks on opposition supporters after the 2008 election
- Thought to be 75 years old, he promises to deliver jobs and is seen as open to economic reforms
- Survived several alleged assassination attempts, blamed on supporters of ex-President Mugabe.