Police arrests dozens amid post-election protests in Indonesia

Indonesian police have arrested at least 20 people accused of provoking riots in Jakarta following official results showing President Joko Widodo had been re-elected, a police spokesman said on Wednesday.

Television footage on Wednesday showed smoke billowing from behind dozens of protesters who were dancing in the street in the Tanah Abang district of central Jakarta.

A separate crowd in front of the election supervisory body threw rocks at police, a Reuters witness said.

The General Election Commission (KPU) on Tuesday confirmed unofficial counts by private pollsters in the April 17 election, which gave Widodo a 55.5 percent share of votes against 44.5 percent for his opponent, former general Prabowo Subianto.

Widodo won more than 85 million votes of a total of 154 million casts in the world's third-largest democracy, but Prabowo told reporters he believed there had been widespread cheating and about 1,000 supporters gathered in Jakarta a day earlier.

On Monday, an election supervisory agency dismissed claims of systematic cheating, citing a lack of evidence. Independent observers have said the poll was free and fair.

Protests that started peacefully on Tuesday turned violent in the evening, forcing police to fire tear gas to disperse the crowd in a main street in the capital, TV footage showed. Cars parked near an apartment housing the police's mobile brigade were set ablaze, media reported.

"As of now, police have arrested more than 20 people we thought were the provocateurs and who did other crimes," said police spokesman Dedi Prasetyo.

Prasetyo said police were checking on reports of casualties but stressed that security officers on the ground, which include military personnel, were not equipped with live bullets.

News website Tirto reported a man died of bullet wounds in Tanah Abang, quoting a doctor at a hospital near the site.

"As per 9 o'clock this morning, there were 200 people hurt being brought to five hospitals," Anies Baswedan, the governor of Jakarta, told broadcaster TVOne.

Indonesian authorities have said 40,000 police and army personnel were on duty across Jakarta in a bid to maintain security. 

On Monday, an election supervisory agency dismissed claims of systematic cheating, citing a lack of evidence. Independent observers have said the poll was free and fair.

A relaxed-looking President Widodo pledged on Tuesday to be a leader for all Indonesians.

"We are grateful and proud that amid our differences, we have been mature in keeping the peace," he said on a visit to a poor neighbourhood of the capital.

Financial markets were mixed, with stocks up nearly 1% and the rupiah off 0.1%.

Andry Taneli, a portfolio manager at Ciptadana Asset Management, said stocks had responded positively to the official result.

"On the other hand there is the concern of Prabowo not accepting the result, but we can see everywhere the police and army are ready to ensure security," Taneli said.

Prabowo had warned the cheating claims could trigger "people power"-style protests, though ahead of the result he had urged supporters in a video to be "peaceful in our struggle".

Prabowo, a retired general, pledged he would "continue to make legal efforts in line with the constitution to defend the mandate of the people".

Sufmi Dasco Ahmad, the legal director of Prabowo's campaign team, confirmed it planned to contest the result in the Constitutional Court.

The losing candidate can lodge a challenge in the constitutional court within three days, otherwise, the election panel will officially declare the winner. Prabowo's challenge to his 2014 defeat by Widodo was rejected.