Jewel Topsfield and Karuni Rompies, Jakarta – Eight Indonesians were arrested for alleged treason on Friday morning ahead of another massive rally calling for Jakarta's governor to be jailed for blasphemy.
Hundreds of thousands of Muslims flocked to Indonesia's national monument, Monas, on Friday morning waving flags bearing the Islamic testament of faith and placards with "Ahok 2 jail" and "the law must be fair".
Police estimated crowd numbers at around 500,000 to 600,000 but some demonstrators claimed on social media the figure was closer to a couple of million.
Among the eight arrested before the rally were Indonesian rock musician Ahmad Dhani and Rachmawati Soekarnoputri, the sister of former Indonesian president Megawati.
Ahmad Dhani had told a similar rally last month that he was "very sad and crying" for having a president who did not respect the habibs (men who claim descent from the family of the Prophet Muhammad) and ulema (Islamic scholars).
Others high-profile identities arrested, according to a Whatsapp group circulated among journalists, were two-star general Kivlan Zein and theatre artist Ratna Sarumpaet.
National police spokesman Martinus Sitompul said the names mentioned in the Whatsapp group were correct. "According to the law they will be detained for 24 hours, then we will see after that if we need to continue keeping them in the police cell or not," he said.
A further two people are facing charges over breaching electronic information laws.
Jakarta Governor Basuki Tjahaja Purnama, a member of Indonesia's Christian and ethnic Chinese minorities popularly known as Ahok, has been named a blasphemy suspect by police after he accused his critics of deceiving voters using a verse from the Koran.
His case dossier has already been submitted to the North Jakarta District Court and he is expected to stand trial within weeks. If convicted, he faces a maximum jail term of five years.
But this has not satisfied his critics and the nation has been restive after last month's protest of up to 200,000 people turned ugly after nightfall. One man died of an asthma attack after tear gas was fired into the crowd, hundreds were injured and vehicles were torched.
Tensions have been high in the capital ahead of Friday's rally, with a social media campaign calling for a run on the banks and hoax news reports and rumours rife on the internet.
The Australian government issued a travel update strongly advising people to stay away from the protest, which it said may turn violent.
Indonesian President Joko Widodo, who was criticised for not meeting demonstrators last month, cancelled a planned state visit to Australia last month and has spent the last few weeks meeting Muslim leaders, police and military and calling for calm.
Later on Friday Jokowi, as the president is popularly known, and other cabinet ministers joined the crowd for prayers.
He thanked the crowd on behalf of the government for conducting the rally peacefully and urged them to safely return to the places from which they had come. "Allahu Akbar (God is the greatest), " the president said.
The rally was peaceful, with volunteers handing out water and snacks, some demonstrators carrying white roses and people respecting signs to keep off grassed areas despite the masses. Many in the crowd, most of whom were wearing white, took selfies of themselves and their friends.
They sang the national anthem and a derivation of a popular song sung at birthdays, with the words: "Arrest Ahok, just do it now." "Why are people coming from outside of Jakarta? Because of our love of the Koran," preacher Bachtiar Nasir told the crowd.
One of the demonstrators, Rohman, told Fairfax Media he had travelled from Tegal in Central Java, some 270 kilometres east of the capital, to attend the rally.
Rohman said he had come to pray for the nation, defend Islam and uphold the law in Indonesia. "What is wrong is wrong," he said. "If he (Ahok) is declared a suspect he should automatically be arrested."
One woman, awed by the size of the crowd, remarked it looked like Mecca. "And still he is not arrested!" she exclaimed.
Melissa Crouch from the University of NSW said post-1998 democratisation had given greater voice to Islamic organisations, who used their freedom to promote an Islamist agenda that claimed to uphold the law.
"In fact, they subvert it," she wrote at policyforum.net. "By demanding the attorney-general arrest Ahok, they are already presuming charges will be laid. By a show of force in the capital, Islamists issue an implicit threat to the judiciary who may hear the case – we will mob your courtroom next. So much for a fair and impartial hearing."
A lawyer for Rachmawati Soekarnoputri told Fairfax Media his client had been picked up at 4.30am and was being interrogated for allegedly committing treason. Yusril Izha Mahendra said the arrest was unrelated to the November 4 rally.
[With Karuni Rompies and Amilia Rosa.]