Joko Widodo vs Prabowo Subianto Photograph:( Agencia EFE )
Defeated presidential election candidate Prabowo Subiant called for President's election victory to be annulled citing "systematic electoral fraud and abuse of power".
Lawyers for Indonesia's opposition leader called on Friday for President Joko Widodo's election victory to be annulled, telling the Constitutional Court it had been achieved through "systematic electoral fraud and abuse of power".
The demand came as the court began a hearing into complaints from defeated presidential election candidate Prabowo Subianto, a retired general with strong support among conservative Muslims, who has refused to concede defeat.
Official results released by the General Election Commission last month showed Widodo had beaten Prabowo by 11 percentage points to win more than 55 per cent of votes in the April 17 poll.
The dispute has brought weeks of uncertainty and deadly protests in the world's third-largest democracy.
"We are filing a lawsuit against the General Election Commission, demanding that it annul its decision on the result of the presidential election," Bambang Widjojanto, the chief lawyer representing Prabowo, told the court.
Prabowo and his campaign team want the Constitutional Court to annul the election, disqualify Widodo and his running mate as candidates or hold another election.
The court is expected to deliver a verdict by June 28.
Widodo has not commented on his rival's accusations of cheating, saying everyone must respect the legal process.
The election agency has said there was no evidence of systematic cheating and independent observers have said the poll was free and fair.
Clashes broke out between Prabowo's supporters and police in the heart of the capital, Jakarta, last month after the official result was announced and eight people were killed and more than 900 injured.
Police have arrested dozens of suspected instigators of the rioting, including a close Prabowo ally accused of orchestrating assassination plots against top government officials.
This week, Prabowo, who has warned of "people power" protests, urged supporters to remain calm through the Constitutional Court proceedings.
About 17,000 police and military personnel have been deployed to prevent a repeat of last month's unrest while the court deliberates.
There was a small, peaceful protest by opposition supporters near the heavily protected court. Some protesters held placards saying "We demand justice!"
Prabowo's legal team pointed to issues with Widodo's campaign financing and use of state apparatus as a campaign tool, saying the election result came about because of "illegal actions, fraud and abuse of power which are structured, systematic and massive".
Prabowo's team also said police and military personnel had been "pressured" to vote for Widodo and the government increased civil servants' salaries as an attempt to buy votes.
Legal representatives for the election agency and Widodo's campaign team were at the hearing.
"There are more theories and assumptions stated in their case than facts ... We can refute all of them," said the chief lawyer representing Widodo, Yusril Mahendra.
The next hearing is on Tuesday.