Prabowo Subianto, the likely loser of Indonesia’s presidential election, has pulled out of the contest, claiming “massive, structured and systematic fraud.”

Prabowo, a former head of Indonesia’s special forces, had claimed victory after last week’s poll, even though the majority of snap exit polls indicated that his opponent, Jakarta governor Joko Widodo, also known as Jokowi, had won by a margin of over 5%., a non-governmental website, estimated that Jokowi had garnered 53.15% of the vote to Prabowo’s 46.84%.

But on Tuesday, Prabowo said he had “no confidence” in the process and pulled his observers out of the official vote count, after trying unsuccessfully to delay the announcement of the official results by the country’s election commission, the KPU.

The KPU had still not formally announced its results at the time of writing.

Prabowo’s announcement threatens to overshadow what had seemed likely to be a peaceful transfer of power in the sprawling archipelago with a population of 240 million, which has witnessed bouts of extreme political violence and instability in the past due to ethnic, religious and economic tensions. Over 130 million votes were cast by the country’s overwhelmingly Muslim population.

Under the Indonesian constitution, Prabowo has three days to contest the results at the country’s constitutional court. It was unclear whether he intended to do so. The English-language paper The Jakarta Post cited top officials at some of the parties that have backed Prabowo as urging him to accept defeat as soon as possible.

Local financial markets sharply reversed gains they had made Monday in anticipation of Jokowi being declared the new president, but appeared to regain some composure toward the end of the trading session.

The dollar spiked 1% higher against the rupiah, although it subsequently retraced about half of that move and is still close to a two-month high. The Jakarta benchmark stock index fell 0.9% on the day, but was still within 1% of the all-time high it hit Monday.