With four per cent of the country's 27,000 ballot boxes counted on Thursday, Saleh had 82 per cent of the votes with Faisal al-Shamlan, the leading opposition candidate, trailing with 16 per cent.
Khalid Sharif, an official in the election commission, said: "Roughly five million of the 9.2 million eligible Yemenis cast ballots." He did not say which areas the boxes came from.
The vote is a major test of Saleh's commitment to democratic reform in Yemen, amid widespread complaints of corruption and the failure to evenly share the country's oil wealth.
The opposition coalition backing Shamlan reported 30 instances of voting irregularities, including observers forced to leave several stations, forced voting, ballot box removal and the intimidation of voters.
But it said its candidate appeared to be doing well.
Muhammad Qahtan, the coalition spokesman, said: "Reports coming from the provinces indicate real progress in the voting in favour of the opposition."
Heightened security surrounded the elections for a president and municipal councils after last week's foiled attacks on energy sites.
Gunfights killed eight people across the country, including an opposition candidate running for a seat on a municipal council.
Eleven others were injured, including two opposition municipal candidates, an election spokesperson said.
There were no immediate official figures on the dead.
Officials say about 100,000 security personnel were guarding voting booths and another 100,000 were on standby to combat any violence.
Saleh has made security a campaign cornerstone.
The opposition based its platform on political and economic reform in a country the World Bank lists as one of the world's poorest.
Nahari, a 40-year-old Jewish carpenter in Raida, 35km north of Sana, said: "He [Saleh] has helped us, made sure we are safe and treated us like other Yemeni citizens.
"Voting is good because it will bring prosperity to the country."
The other three hopefuls, two of whom are pro-government, have little political experience and are standing as independents.
Saleh, a military officer, has ruled Yemen since its unification in 1990.