Afghans have headed to the polls for a second round of voting to elect a successor to President Hamid Karzai.
Saturday's vote pits former Foreign Minister Abdullah Abdullah against ex-World Bank economist Ashraf Ghani after neither secured the 50 percent majority needed to win outright in the first round on April 5.
Security has been tightened across the country after Taliban fighters threatened to attack the election, which they have condemned as a US-sponsored charade.
Omer Daudzai, the country's interior minister, said in a media briefing that there had been around 150 attacks of various intensity across the country since the polls opened. The Afghan security forces have been able to deflect most of the violence, he said.
Both candidates, as well as incumbent Hamid Karzai, voted early on Saturday, though most pollng stations remained relatively quiet throughout the morning.
Al Jazeera's Imtiaz Tyab, reporting from Kabul, said there had been reports of rocket attacks in the capital shortly after polls opened.
He said there was a "huge security presence" in Kabul, with checkpoints and security forces all over the city.
About 200,000 soldiers from the Afghan army have been deployed at polling centres across the country.
'Good so far'
Afghan officials and international allies are hoping for a repeat of the successful first-round vote in April, when the Taliban failed to launch a single high-profile attack and voter turnout was more than 50 percent.
Shortly before polls closed on Saturday, Nicholas Haysom, the deputy chief of the UN mission, described the vote as "good" so far.
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Abdullah secured 45 percent of the first-round vote with Ghani on 31.6 percent, after coming out top of an eight-man field.
Harsh terrain and poor roads make holding an Afghan election a major challenge, with thousands of donkeys used to transport ballot boxes to remote villages.
Counting the vote will take weeks. The preliminary result is due on July 2 and the final result on July 22.
Ahead of the election, the Taliban said polling booths would be targeted in "non-stop" assaults.
Police and soldiers have been searching almost every car on the roads of the capital, and Afghan officials expressed confidence in the security forces that have been trained by the US-led military coalition.
"The level of threats is higher compared to the first round," Interior Minister Omar Daudzai said. "But we have gained far more experience and we have better equipment and are in a much better position to prevent any possible attack by terrorists."