By Agence France-Presse
The Islamic Defenders Front (FPI) has in recent years become the face of hardline Islam in the world's most populous Muslim-majority country, growing in influence despite being a fringe organisation whose extreme views are rejected by most.
The group has raided bars selling alcohol during the holy month of Ramadan, forced the cancellation of a concert by Lady Gaga -- whom they dubbed "the devil's messenger" -- with noisy protests, and led demonstrations against the Miss World beauty pageant when it came to Indonesia.
Led by firebrand cleric Rizieq Shihab, the FPI helped organise recent mass rallies -- which attracted conservative and moderate Muslims -- against Jakarta governor Basuki Tjahaja Purnama, an ethnic Chinese Christian, who is on trial for allegedly insulting Islam.
The protest movement against Purnama -- accused of insulting the Koran while campaigning for re-election in polls later this month -- propelled the hardliners from being a marginal group to the centre of national politics, alarming observers and some in the government.
Now authorities are seeking to put the muzzle back on the radicals, with police stepping up an investigation into Shihab in a move seen as supported by President Joko Widodo and his administration.
"This is unprecedented, it is the first time that the president and the government is openly challenging this Islamist group," Tobias Basuki, an analyst from Jakarta think-tank the Centre for Strategic and International Studies (CSIS), told AFP.
Last week police named the cleric a suspect for allegedly defaming Indonesia's founding president, Sukarno, and the state ideology in a speech several years ago, meaning authorities believe there is enough evidence for him to stand trial.
'Make a stand'
Basuki said successive governments had shied away from cracking down for fear of being accused of attacking Islam but the current administration decided to "make a stand" as concerns mounted about the hardliners' influence.
The radicals have reacted angrily. Hundreds have rallied in support of Shihab -- who has served two short jail terms in the past -- whenever he is hauled in for police questioning.
Authorities "want to stifle an Islamic people's movement, which is demanding justice against a blasphemer", FPI spokesman Slamet Maarif told AFP.
While they often hit the headlines with their colourful, noisy protests, the FPI does not have a huge following in the country of 255 million people.
The group claims to have four million members but Ian Wilson, an expert on the FPI from Australia's Murdoch University, estimated the figure at a maximum of 200,000.
That is a fraction of the tens of millions who are members of Indonesia's two major, moderate Muslim organisations, Nahdlatul Ulama and the Muhammadiyah.
But efforts to tackle the FPI are complicated by its long history of links to some members of the establishment, who have in the past used the group to carry out their dirty work, said Guntur Romli, a progressive Muslim activist.
"Some in the bureaucracy and opportunistic politicians like the group as they can be used as a weapon, while claiming to act in the name of Islam," said the activist, who is also a member of Purnama's election campaign team.
The FPI was founded in 1998 as Indonesia transitioned from dictatorship to democracy, and experts believe the military and police had a hand in its formation, hoping they could use the group against their enemies during the tumultuous period.
The police have on many occasions been seen working with the FPI when it conducts raids, or standing by and taking no action, while members of the elite sometimes allegedly hire the group to help in their murky business dealings.
While the current crackdown is viewed as long overdue, it may not do away with the FPI forever, with analysts doubting the government will disband the group as the process is complicated.
They believe the moves against Shihab are aimed at preventing trouble in the coming months during the Jakarta election and Purnama's court case.
But once the current controversies blow over, "it is likely that it's going to be back to business as usual," Basuki of CSIS warned.