Zimbabwe's main opposition leader has said his party is "ready to form the next government" following the country's first general election since Robert Mugabe was removed from power.
Nelson Chamisa, 40, and 75-year-old president Emmerson Mnangagwa were the main contenders in Monday's election, which several observer groups have said is too close to call.
Mr Mnangagwa was viewed as the frontrunner, although the latest opinion polls showed a tight race. There will be a runoff on 8 September if no candidate wins more than half the votes.
"Winning resoundingly... We now have results from the majority of the over 10 000 polling stations," Mr Chamisa wrote on Twitter early on Tuesday morning. "We’ve done exceedingly well. Awaiting ZEC to perform their constitutional duty to officially announce the people’s election results and we are ready to form the next gvt."
Mr Mnangagwa later tweeted he was "delighted" by high voter turnout and that he had received "extremely positive" information from Zanu-PF representatives on the ground.
The Zimbabwe Electoral Commission (ZEC), which said on Monday voter turnout had averaged 75 per cent, will announce official results within five days.
The election came after an extraordinary intervention my Mr Mugabe, who turned against Mr Mnangagwa, his former vice president, and the Zanu-PF party he led for so long.
In his first public appearance since being removed from power, he praised Mr Chamisa, who leads the Movement for Democratic Change (MDC), as the only candidate who could “return legitimate government to the country”.
The former anti-colonial fighter went on to decry the “evil and malicious characters” who deposed him, and stridently defended his wife Grace. Ms Mugabe, who was by her husband’s side during the press conference in which he made the comments, is accused of serious corruption but Mr Mugabe demanded critics “leave her alone”.
Several civil society groups are collating results from 10,985 polling posts in parallel with the ZEC, but are not allowed to release results before the commission. A source at one group said it was too early to call a winner but it was looking "very close".
Mr Mnangagwa's spokesperson, George Charamba, and Zanu-PF spokesperson Simon Khaya-Moyo did not respond to calls for comment.
In the capital Harare, an MDC stronghold, results posted outside some polling stations seen by Reuters showed Mr Chamisa winning by wide margins but Mr Mnangagwa was expected to claw back ground in the ruling Zanu-PF rural heartland.
Urban results tend to emerge quicker than those from rural outposts, where communication is poor.
In some rural constituencies in the east and south of the country, counting of votes was still ongoing but was expected to end early on Tuesday, some parliamentary candidates said.
Some 5.5 million people were registered to vote and dozens of people waited in line on Monday to vote outside many polling stations in Harare, the capital.
“I want to do this and get on with my business. I am not leaving anything to chance. This is my future,” said Emerina Akenda, a first-time voter.
“We need change because we have suffered a lot here,” said 65-year-old Mable Mafaro while voting in Harare. “We have suffered a lot. That’s all.”
The election winner faces the task of putting Zimbabwe back on track after 37 years of rule by Mr Mugabe, a period tainted by corruption, mismanagement and diplomatic isolation that caused crises in a country that once had one of Africa's most promising economies.
A credible vote is essential if Zimbabwe is to exit painful sanctions and secure the donor funding and investment needed to stem chronic cash shortages.
The run-up to Monday's vote was largely peaceful compared to past elections under Mr Mugabe, where the ruling party and war veterans were accused of violence against opponents.
Dozens of people were killed ahead of a runoff in 2008 between Mr Mugabe and MDC-founder Morgan Tsvangirai, who died of cancer in February.
Mr Mugabe emerged on the eve of the election to announce he would vote for the opposition, surprising Mr Mnangagwa who accused him of striking a deal with Mr Chamisa.
Additional reporting by agencies.
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