Indonesia Defence Minister Prabowo Subianto has declared victory in a presidential election after unofficial vote counts showed him with a huge lead that could see him win in a single round.

Political veteran Prabowo, a former special forces commander, had about 58 per cent of votes according to four pollsters, based on ballots counted in a sample of voting stations nationwide. The number of ballots tallied ranged from about 78 per cent to 93 per cent by early evening local time.

In a rousing speech before supporters that drew huge applause, Prabowo vowed to create a government consisting of “the best Indonesians” and said it was a victory for all of the people.

Rivals Anies Baswedan and Ganjar Pranowo trailed with about 25 per cent and 17 per cent respectively, according to independent pollsters conducting “quick counts”, which in previous elections have proven to be accurate.

A preliminary count by the election commission was far slower and showed Prabowo securing 57.7 per cent of votes with about six per cent of ballots recorded.

The contest pitted the two popular former governors against the pre-election frontrunner Prabowo, who was feared in the 1990s as a top lieutenant of Indonesia’s late strongman ruler Suharto.

Crucially, Prabowo has the tacit backing of the wildly popular incumbent Joko Widodo, who is betting on his former rival as a continuity candidate to preserve his legacy, including a role for his son Gibran Rakabuming Raka as the defence minister’s running mate.

Anies and Ganjar urged the public not to draw conclusions on the outcome and to await the official result, which is expected by March 20 at the latest.

The campaign teams of Ganjar and Anies said they were investigating reports of electoral violations, both calling it “structural, systematic and massive fraud”. They did not provide evidence.