A tearful governor of Jakarta denied on Tuesday he had intended to insult the Holy Quran at the start of his blasphemy trial in the Indonesian capital, which is seen as a test of religious freedom in the world largest Muslim-majority nation.

Around 100 Muslim protesters calling for the jailing of Governor Basuki Tjahaja Purnama, an ethnic Chinese Christian, chanted “God is great” outside the court.

Authorities have pledged tight security for the trial after tens of thousands of Muslims, led by hardliners, took to the streets in November and December, to call for Purnama's arrest and to urge voters not to re-elect him in February.

The rallies, with over 150,000 participants each, were the biggest Jakarta has seen in nearly two decades.

Purnama told the court that he had not intended any insult when he made comments about his opponents' use of the Holy Quran in political campaigning. He denies wrongdoing but has apologised for the remarks.

“It is clear what I said in the Thousand Islands was not intended to interpret the (Holy Quran), moreover to insult Islam or the ulema,” claimed the governor, who was dressed in a batik shirt.

Purnama said that his comments were targeted at rival politicians trying to get an unfair advantage in the election by saying that voters should not support a non-Muslim.

Purnama is running for re-election against two Muslim candidates.

The trial was aired live on television and there were also supporters of the governor, whose nickname is Ahok, outside the court.

“He is absolutely suited to be governor. The city has come a long way in terms of development...,” said Charles Simanjuntak, 46, a supporter of the governor who does not believe he committed blasphemy.

Among the protesters opposed to the governor, one group held a placard reading “Jailing Ahok = fair government”.

President Joko Widodo, seen as an ally to Purnama, has blamed “political actors” for fuelling the protests, but declined to elaborate.

Widodo has faced widespread criticism for not doing enough to protect the country's religious minorities.

Indonesia has the world's largest Muslim population, but the country of 250 million also has sizeable Christian, Hindu and Buddhist communities and dozens of groups that adhere to traditional beliefs.

Purnama, if found guilty, faces up to five years in prison. Almost all blasphemy cases in recent years have ended in conviction.

As Jakarta's first ethnic Chinese governor, Purnama won kudos for shaking up the city's sleepy bureaucracy and for taking steps to ease the city's notorious traffic.

But his abrasive language and insistence on clearing the city's slums has alienated many voters.

Recent opinion polls showed Purnama, once the frontrunner in the race to lead Jakarta, has now slipped to second place, behind Agus Yudhoyono, the son of former president Susilo Bambang Yudhoyono.