Hardliners have mounted a sometimes violent anti-Ahmadiyah campaign
The Indonesian government has announced tough restrictions on followers of the minority Ahmadiyah sect.
In the decree, the Ahmadiyah are warned they risk five years in jail if they do not stop spreading unorthodox beliefs and return to mainstream Islam.
The Indonesian constitution guarantees freedom of religion.
This latest move is widely seen as bowing to Islamic hardliners, who have stepped up a sometimes violent campaign against the nation's 200,000 Ahmadiyah.
Last week dozens of pro-tolerance demonstrators were attacked by members of a militant Islamic group - and on Monday several thousand hardline Muslims again took to the streets in support of banning the sect.
The Ahmadiyah have views that are seen as controversial by mainstream Islamic society.
A widespread belief among sect members is that their founder, Mirza Ghulam Ahmad, was the final prophet of Islam - and not Muhammad.
The religious affairs minister made the long-awaited announcement in a joint decree with the country's interior minister and attorney general.
The text of the decree orders the sect to "stop spreading interpretations and activities which deviate from the principal teachings of Islam," reported the news agency AFP.
Such activities included "the spreading of the belief that there is another prophet with his own teachings after Prophet Muhammad".
There has been fierce debate in Indonesia over whether the country's constitution allows the banning of religious practices, says the BBC's Lucy Williamson in Jakarta.
The preamble to the decree insists that the decision is in line with Indonesia's constitutional guarantees on freedom of religion, and with domestic and international laws on human rights, she says.
But many Indonesians are likely to disagree.