Early results from Iran’s presidential election put the reformist-backed candidate, Hassan Rouhani, in the lead, the BBC reports.
Official figures give him more than half the 12 million votes counted so far – well ahead of second-placed Tehran mayor Mohammad Baqer Qalibaf.
Mr. Rouhani could win in the first round if he finishes with more than 50.1%.
Electoral officials said turnout was high among the 50 million Iranians eligible to vote on Friday for a successor to Mahmoud Ahmadinejad.
His eight years in power have been characterised by economic turmoil and Western sanctions against Iran over its nuclear programme.
Final results are expected later in the day.