Rights watchdog Kontras called for the Acehese administration to "annul all practices of physical criminalisation such as caning" and revise its Islamic legal code after a farmer was publicly caned for gambling.
Other activists noted the province's sharia, or Islamic, regulations were being selectively applied and mostly affected poor people. A rich businessman would never have been caned for gambling, they said.
The farmer was among four men who were arrested in December for placing bets up to 1,000 rupiah (11 cents) on a game of dominoes. The three others escaped punishment but the farmer received six strokes of the cane outside a mosque on Friday.
Kontras said local laws in semi-autonomous Aceh, a deeply Islamic province on the northern tip of Sumatra, could not contravene Indonesia's international treaty obligations.
"This is an absolute obligation for the Aceh administration as Aceh is an integral part of the republic of Indonesia, which is a signatory to human rights conventions," Kontras said in a statement.
The caning controversy is another blow to the sharia police in Aceh after three officers were charged with gang-raping a woman in custody last month.
Human rights activist Teuku Achmad Fuad Haikal said Aceh's religious police were "discriminating against common people".
"The Islamic law seems to apply only to common folk. The men faced caning for making 1,000-rupiah bets while those who gamble millions of rupiah aren't touched by the law," he said.
"Several government officials and wealthy people who were detained for violating the Islamic law in the past weren't caned."
Women's rights activist Evi Narti Zein said caning was "inhuman" and the authorities "should have matched the severity of the punishment to the gravity of the offence".
