Hundreds more activists have gone into hiding in Zimbabwe as security agencies intensify a crackdown launched shortly after the election 10 days ago.
Millions of people cast votes in the poll, the first since the ousting of Robert Mugabe last year.
The victor was Emmerson Mnangagwa, a former aide to Mugabe and a stalwart of the Zanu-PF party, which has ruled since independence from Britain in 1980.
Nelson Chamisa, the opposition Movement for Democratic Change leader, has said his party will challenge the “illegitimate and fraudulent” election in the courts.
The poll was seen as a potential turning point for Zimbabwe, which desperately needs foreign investment to avoid economic breakdown.
But hopes for dramatic and immediate change have been dashed by violence and alleged human rights abuses since the election.
Tendai Biti, a senior MDC leader, was arrested at the country’s border with Zambia on Wednesday, while further reports of detentions of and assaults on activists emerged.
Six people died last week when soldiers opened fire on MDC protesters in central Harare.
According to dozens of testimonies gathered by the Guardian, security forces have since harassed hundreds of MDC leaders and activists, arbitrarily detaining and beating scores of people.
At the weekend, soldiers moved through neighbourhoods of Harare and surrounding towns, targeting opposition supporters, smashing property and assaulting dozens of people.
Last week the homes of leaders were surrounded by unidentified masked and armed men during the night, and homes of activists were invaded by gangs shouting pro-government slogans.
In the past 48 hours, dozens of independent media activists have gone into hiding, along with several NGO workers fearful of detention.
Ashley Pfunye, 21, a student leader, said he had gone into hiding after a warning that “the military” were looking for him. At least one of his friends had already been detained, he said.
“The army has a list and I am on it,” Pfunye told the Guardian. “I rang my mum to tell her she would not hear from me for a while and went underground. It was a hard call to make.
“I don’t know when we’ll speak again. If I’m found, I will disappear and it might be forever. I am frightened, but it is what politics here in Zimbabwe is all about.”