Tens of thousands of security personnel fanned out across Jakarta Friday as a court heard a defeated presidential challenger’s claim that Indonesia’s 2019 election was rigged — allegations that spawned deadly rioting last month.

Ex-general Prabowo Subianto lodged an appeal that claimed his loss to incumbent leader Joko Widodo on April 17 was the result of massive electoral fraud and irregularities in the vote counting. Indonesia’s election commission has said Widodo won 55.5 per cent of votes in the world’s largest Muslim-majority country against Subianto’s 44.5 per cent.

Election officials and analysts have discounted Subianto’s rampant cheating claims, and he lost a similar court battle in 2014 when Widodo defeated him.

But peaceful protests against the official result erupted into two nights of street battles between police and rioters in Jakarta last month, leaving eight people dead and hundreds injured in the capital’s worst violence in years.

On Friday, the constitutional court began hearing evidence from Subianto’s legal team. A decision on whether the evidence is strong enough to proceed with the case could be reached as early as Friday afternoon.

National police spokesman Dedi Prasetyo said 32,000 police officers and soldiers had been deployed across Jakarta in anticipation of “any potential for disruption that could interfere with proceedings”. Police were equipped with shields, tear gas and water cannons, but not live ammunition, he said.

“The approach remains a soft approach if there is a demonstration in front of the Constitutional Court,” he told AFP.

Indonesian police have been under the spotlight after online videos surfaced that appeared to show officers beating some protesters.

There are also questions about how the demonstrators — including a 15-year-old high school student — died.

Police have insisted they did not shoot live rounds, but instead used rubber bullets, water cannons and tear gas to push back the crowds. Some of the dead were reported to have had gunshot wounds.

Meanwhile, several Subianto allies have been arrested recently, including former army general Kivlan Zen over his alleged links to the Jakarta riots.

Police have also aired video from several arrested suspects who claimed that Zen masterminded a failed plot to kill four senior government officials, including its chief security minister and the president’s top intelligence adviser.

A total of six people — arrested before they could carry out the killings — planned to murder the officials and an election pollster in a bid to plunge the country into chaos, police have claimed.