Agathon Rwasa, Burundi's opposition leader and deputy speaker of Parliament has filed a petition at the country's constitutional court disputing the win of the ruling CNDD-FDD party's Evariste Ndayishimiye.

Mr Ndayishimiye won the May 20 presidential election with 68 per cent of the vote against Mr Rwasa's 24 per cent.

"If the constitutional court rules in their favour I will move to the African Court because all the results that were announced by the electoral commission were wrong," said Mr Rwasa.

The country's Catholic Church deployed 2,716 observers countrywide, and has also expressed misgivings on the election process and its outcome.

However the chairman of the Independent Electoral Commission, Pierre Claver Kazihise, said that members of the Catholic church observer mission weren't well educated and informed about the electoral process.