Indonesian Defence Minister Prabowo Subianto has a strong lead in the race for the presidency of Indonesia, preliminary results collated by government-approved pollsters showed on Wednesday after polls closed.

With around 60 percent of sample votes tallied in so-called "quick counts" that have previously proven reliable, two independent pollsters showed Prabowo on more than 55 percent of the vote.

Pollster Poltracking showed Prabowo at 59.77 percent of the vote in the preliminary count and Cyrus Network-CSIS had him at 58.62 percent.

Securing more than 50 percent of the vote would be enough to avoid a second-round run-off against one of his two election rivals Anies Baswedan or Ganjar Pranowo.

Official results are expected next month. Tens of millions of people voted in the presidential poll, with Prabowo the frontrunner for months.

The vote across 800,000 polling stations ended at 1.00pm local time in western Indonesia, while some in Jakarta remained open after the capital was inundated by thunderstorms.

"Alhamdulillah (Praise be to God), we hope the election can go in one round," said Nusron Wahid, secretary of Prabowo's campaigning team, commenting on the latest quick counts.

The world's biggest single-day election has included nearly 259,000 candidates vying for 20,600 posts across the archipelago of 17,000 islands, but the focus has been firmly on the race to replace President Joko Widodo, whose influence could determine who takes the helm of the world's third-largest democracy.

The early lead will be a big boost for Prabowo, who is contesting his third successive election after twice losing out to the hugely popular Widodo, who cannot run again because of term limits.

Jokowi, as the incumbent is known, is tacitly backing and betting on his former rival as a continuity candidate to preserve his legacy, including a role for his son Gibran Rakabuming Raka as Prabowo's running mate.

Two surveys issued last week gave Prabowo just over 50 percent support, with Anies and Ganjar 27 and 31 points adrift, respectively, though the quick counts point to a stronger lead.

Widodo's successor will inherit an economy with impressive growth and ambitious infrastructure projects, including the ongoing transfer of the nation's capital from congested Jakarta to the frontier island of Borneo at a staggering cost exceeding US$30 billion. (Agencies)