Indonesia has banned the Hizb ut-Tahrir group under a controversial presidential decree that gives officials the authority to disband organisations deemed to threaten national unity.
The legal status of Hizb ut-Tahrir, which campaigns for the country to adopt Islamic law and become a caliphate, was revoked on Wednesday to protect Indonesia's unity, according to Freddy Hari, the director-general of the Ministry of Justice and Human Rights.
The group condemned the ban and said it "will not remain silent", vowing to challenge the decision in court.
The government's move comes a week after President Joko "Jokowi" Widodo signed a presidential decree that gives the government almost unfettered power to ban groups that go against "national unity and the existence of the Indonesian nation".
Legal expert Refly Harun said it was the first time in the reform era that the government had disbanded an organisation without due process of law.
"The presidential decree is a blank cheque for the government to disband any group without due process of law," he told the AFP news agency.
The decree followed months of sectarian tensions and protests, partially organised by Hizb ut-Tahrir, which saw Jakarta's Christian governor Basuki "Ahok" Tjahaja Purnama sentenced to two years in prison for blasphemy against Islam.
The move is seen as targeting hardline Islamic organisations and has been criticised by human rights groups as a threat to freedom of association.
About 2,000 people from Islamic groups protested against the order in Jakarta on Tuesday, denouncing the government as repressive and tyrannical. Another protest is planned for Wednesday.
'This is tyranny'
In May, the government had said it planned to ban Hizb ut-Tahrir because its activities were not in line with the state's secular ideology and were "causing friction in society".
Following last week's decree, Hizb ut-Tahrir members vowed to seek a judicial review in constitutional court.
"This is tyranny," said Ismail Yusanto, a spokesman for the group in Indonesia.
"The move just shows an arbitrary action aimed at disbanding Hizb ut-Tahrir.
"[Hizb ut-Tahrir Indonesia] is a legal religious organisation and has been spreading its messages peacefully, in an orderly manner, in accordance with the law."
Hizb ut-Tahrir, which says it uses non-violent means to achieve its goal of a caliphate, is active in Australia and the UK but is banned in several Middle Eastern and Central Asian countries.
The group is estimated to have tens of thousands of members in Indonesia.