Harare, Zimbabwe - Zimbabwe's opposition leader Nelson Chamisa has rejected President Emmerson Mnangagwa's election victory as fraudulent, saying he will pursue legal and constitutional means to challenge the result.
His comments on Friday came as Mnangagwa denied the opposition claims, hailing "a free, fair and credible election".
In the early hours of Friday, the electoral commission said Mnangagwa, of the ruling ZANU-PF party, won 50.8 percent of votes in Monday's presidential poll. Chamisa, of the opposition Movement for Democratic Change (MDC) Alliance, came in second, at 44.3 percent.
"We are not accepting fake results. We are not accepting this fiction. We want a proper result to be announced," Chamisa told reporters in the capital, Harare, on Friday.
"We will pursue all means necessary - legal and constitutional - to make sure that we protect the people's vote," he added.
The 40-year-old described the electoral body's declaration of Mnangagwa, 75, as the winner of the first poll since long-term leader Robert Mugabe left office in November 2017 as "regrettable".
His press conference was delayed for more than an hour after riot police shouting "clear out" chased reporters who gathered at Harare's Bronte Hotel.
Mnangagwa: Zimbabwe enjoying democracy
Mnangagwa, a former spy chief and a ZANU-PF veteran, denounced the opposition claim that the vote was rigged.
"We won the election freely and fairly, and have nothing to hide or fear. Anyone is free to address the media at any time," Mnangagwa wrote on Twitter.
In a press conference that followed that of Chamisa, Mnangagwa repeated that the election was free and fair and added that "our freedom and openness were there for all to see".
"In regards to accepting or not accepting the results, Zimbabwe is enjoying democracy. We have introduced comprehensive democracy. Any member of the public or any political party, can proceed in terms of the Constitution and the electoral act to challenge the result in the courts," he said.
"I believe that these leaders or individuals or organisations are free in my view to approach the courts," added Mnangagwa.
Elections observers from the European Union and the United States were allowed into the country and monitor the vote for the first time since 2002.
Observers from the EU said there was "un-level playing field" in the poll and "intimidation of voters".
"These elections were seen as a critical test of Zimbabwe's reform process," Elmar Brok, the EU mission's chief observer, said on Wednesday.
"In some senses, up to this point, the conduct of the polls has had a number of positive features, but in other senses, serious concerns remain," added Brok.
Previous elections in Zimbabwe have been marred by intimidation and threats, but Monday's vote was relatively peaceful.
Things however turned violent on Wednesday after Zimbabwe's electoral commission said the ruling party had won the parliamentary election - also contested on Monday.
ZANU-PF, which has ruled the southern African country since independence in 1980, won a clear majority in the 210-seat parliament by securing 145 seats.
The MDC came in second with 63, while the National Patriotic Front and an independent candidate also picked up one seat each.
Meanwhile, neighbouring South Africa's President Cyril Ramaphosa congratulated Mnangagwa on his victory and urged Zimbabweans to accept the poll results.
"We urge the people of Zimbabwe to accept the outcome of the election, or follow the legal route should they wish to challenge it," Ramaphosa said on Twitter on Friday.
On Thursday, the United Nations called on both the ruling party and the main opposition to "exercise restraint" following the landmark poll.
Follow Hamza Mohamed on Twitter: @Hamza_Africa