Indonesia has been criticised by US groups and others after a murderous attack against supporters of the minority Ahmadiyah Muslim sect.
A mob attacked sect members, killing at least three, while police either fled or stood by watching.
A body which advises the US government on religious freedom has said Indonesia must act against extremist attacks.
A 1965 blasphemy law, and a 2008 anti-Ahmadiyah decree, must be revoked, it said, and the attackers punished.
"This is just more deadly evidence that blasphemy laws are the cause of sectarian violence, not the solution," said Leonard Leo, chair of the US Commission on International Religious Freedom.
"Indonesia is a tolerant county that should be more intolerant of extremist groups," he said. "It's time the Indonesian government brings them to account for the violence and hatred they spread."
New York-based Human Rights Watch echoed the calls, saying the Indonesian authorities should be watching the video of the attack carefully to catch the perpetrators.
"There needs to be a full investigation into why the police absolutely failed to prevent this mob from going on a violent rampage," said Elaine Pearson, deputy Asia director at Human Rights Watch.
The group obtained and helped to disseminate the video which shows the attack, in which Muslim protesters beat three men to death.
"How many Ahmadiyah have to die at the hands of mobs before the police step in," Ms Pearson said.
"The Indonesian government should end this wave of hate crimes and immediately revoke the 2008 anti-Ahmadiyah decree, which encourages these vicious attacks."
A spokesman for the police, Boy Rafli Ahmad, said that although 30 police officers had been present they were greatly outnumbered by the 1,000-strong mob.
"This brutal attack on Ahmadiyya followers reflects the continued failure of the Indonesian government to protect religious minorities from harassment and attacks and to hold the perpetrators accountable," said Donna Guest, Asia-Pacific Deputy Director at Amnesty International.
The Jakarta Post newspaper said "barbaric" and "sadistic" were the two words most commonly used to describe the onslaught in Umbulan village, Pandeglang, Banten.
"But the killings may not be the last, and violence may continue increase as the government remains at a loss in addressing the issue," it wrote.
The Indonesian government condemned the attack and has promised an investigation.
But critics have frequently asserted that President Susilo Bambang Yudhoyono has not taken a strong stand against extremist Islamic groups for fear of their wealthy and military backers.
The decree of 2008 stopped short of banning the sect but threatens worshippers with jail if they continue to spread their beliefs.
The religious minister has called for the dissolution of the sect, mainly because of their belief that their founder, and not Muhammad, was the last prophet.
The Indonesian constitution guarantees freedom of religious expression.
Indonesia has the world's largest Muslim population but it is a secular country. But the government has been accused of caving into their demands since it relies on the support of Islamic parties.