Joko Widodo has been re-elected and declared the winner of the 2019 Indonesia presidential election.

And his opponent Prabowo Subianto has refused to concede defeat after claiming widespread cheating.

Confirmation

An official count showed on Tuesday, May 21, that Jokowi won re-election in April's poll.

The result released by the General Election Commission (KPU) confirmed unofficial counts by private pollsters in the April 17 election.

Widodo got 55.5 percent of votes against 44.5 percent for retired general Prabowo.

Widodo won more than 85 million votes of a total of 154 million cast in the world's third-largest democracy.

Claims of fraud

The Prabowo campaign made repeated claims of fraud and said it would launch a legal challenge.

The opposition candidate even claimed victory despite the quick counts not being in his favour.

"We decided the number two (Prabowo) ticket will lodge a lawsuit with the Constitutional Court," Sufmi Dasco Ahmad, the legal director of Prabowo's campaign team, told reporters.

The results were announced more than a day earlier than expected, after the agency worked into the early hours of Tuesday.

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.

A witness for the team and the leading opposition party refused to sign and validate the official results.

"We won't give up in the face of this injustice, cheating, lies, and these actions against democracy," said Azis Subekti, the witness.

Claims of cheating dismissed

A day before the official announcement of a Jokowi win, the election agency dismissed claims of systematic cheating.

It cited a lack of evidence, and independent observers and analysts have said the poll was free and fair.

People could take to streets

Prabowo had warned the cheating claims could trigger "people power"-style protests.

But it was not immediately clear if planned protests by Prabowo's supporters would go ahead.

The military man had urged supporters to be peaceful in a video issued ahead of the result.

"I remind you, we must be peaceful in our struggle, we must be free from violence," Prabowo said in the video, which media website Kumparan.com said it received on Tuesday.

Authorities have tightened security.

The government and police have urged protesters to keep the peace and vowed action against anyone stirring unrest.

Dozens of militant Islamists suspected of planning attacks to create mayhem during demonstrations were detained.

Police have rolled out extra barbed wire and readied armoured trucks and water cannons around the election agency.

Some schools in Jakarta have shut this week and offices allowed staff to work from home.