JAKARTA (REUTERS) - Six supporters of Indonesian Islamist cleric Rizieq Shihab were killed in a shootout on Monday (Dec 7), police said, raising worries the clash could reignite tensions between authorities and Islamist groups in the world's biggest Muslim majority country.

Since his return from self-exile in Saudi Arabia last month, Mr Rizieq has declared plans for a "moral revolution" causing unease in President Joko Widodo's administration as Indonesia battles the coronavirus pandemic and an economic recession.

Who is Rizieq Shihab?

Hard-line Islamist cleric Rizieq Shihab has for years cut a controversial figure in Indonesian politics.

He heads the Islamic Defender's Front (FPI) group.

He was jailed in 2008 for inciting violence and left Indonesia in 2017 after facing charges of pornography, and insulting state ideology, which were later dropped.

With a reputation for raiding bars, brothels and violently cracking down on religious minorities, the FPI has since become politically influential.

In 2016, Mr Rizieq was the figurehead of the mass 212 movement against Jakarta's former Christian governor, Mr Basuki Tjahaja Purnama, or Ahok, who was jailed on charges of blasphemy for insulating Islam.

The 2016 mass rallies, the biggest since the fall of Suharto in 1998, raised concern about the rise of identity politics and political Islam.

The President, popularly known as Jokowi, viewed the rallies as one of the biggest threats to his government.

What happened in shootout?

When Mr Rizieq returned to Indonesia, he was met by tens of thousands of supporters and in subsequent days, held several events also attended by thousands.

Hard hit by the pandemic and amid restrictions on mass gatherings, police have twice summoned Mr Rizieq for questioning over alleged violation of health protocols.

The cleric has ignored the requests, most recently on Monday (Dec 7) - the day of the shootout, in which police said six of his supporters were killed.

Police say they were tailing a convoy of Mr Rizieq's supporters on a Jakarta highway just after midnight after hearing they were preparing to mobilise, when firearms were pointed at them.

Police say they acted in self-defence when they opened fire and killed six people.

The FPI claims Mr Rizieq was traveling to a dawn prayer when they were attacked by unknown assailants who "abducted" six of his bodyguards.

An FPI spokesman described the incident as an"extrajudicial killing".

Amnesty International Indonesia and Indonesia Police Watch have called for an independent investigation.

How big a force is Islam in Indonesian politics?

As the world's biggest Muslim-majority nation Islam has always been important in Indonesian politics.

Every president has been Muslim.

The 2016 rallies against the Jakarta governor saw Islam take on an increasingly prominent political role.

In a move widely seen as an attempt to appeal to Muslim voters, president Jokowi chose a senior Islamic cleric, Ma'ruf Amin, as a his vice presidential running mate in 2019.

To further neutralise the threat posed by Islamists, in 2019, Jokowi appointed fiery former general Prabowo Subianto as defence minister.

Mr Prabowo had harnessed support from Islamist groups when running against Jokowi.

While Mr Rizieq was overseas, hard-line Islamic groups such as the FPI have been relatively quiet and Jokowi had, until the pandemic hit, been able to govern without too much pushback.

What could happen now?

Political analysts say given the opposition vacuum, the coronavirus and the first recession in 22 years, Mr Rizieq may harness frustrations with the government and pose a threat.

The 55-year-old cleric has already met several key opposition figures and there is a sense that politicking for the 2024 election is already under way.

More immediately, Monday's fatal clash with police may create six "martyrs" and give the FPI a rallying point.

According to sources and analysts that spoke to Reuters the government grossly underestimated Mr Rizieq's continued appeal and following his reception was aware it would have to carefully calibrate its response, fearing if it cracked down too hard it may backfire.

Despite more vocal backlash from pluralists and moderate Islamic groups such as the MUI (Indonesia Clerics Council) towards Mr Rizieq this year, Monday's incident was unlikely to have met the careful approach the president and his key ministers had been aiming for.