Nurdin Hasan, Banda Aceh – Eighteen men and one woman were caned in the eastern Aceh town of Langsa on Thursday, less than a week after Amnesty International called for an end to the practice.

The caning took place in the town's Merdeka Park and was watched by more than a thousand onlookers.

Irvon, head of the general crimes unit at the Langsa Prosecutors' Office, said most of those caned had been convicted of gambling after being found selling coupons for togel, a type of illegal lottery.

"Most of them were dealers and only a few were players," he said. He added that each of them had received six strokes of the cane, including the woman.

Irvon said a 20th person arrested in the case, believed to be the ringleader of the lottery racket, had not been caned because he was not Muslim and would stand trial on criminal charges at the Langsa District Court.

The others had been tried at the Shariah court, which calls for punishments of between six and 12 lashes for gambling.

The caning came four days after human rights group Amnesty International urged the central government to repeal an Aceh bylaw that allows the form of corporal punishment for crimes deemed to be against Islamic law.

"It seems that Aceh's authorities are increasingly resorting to public caning in violation of international law," Sam Zarifi, Amnesty's Asia-Pacific director, said in a statement on Sunday.

"The Indonesian government must act to stop these punishments, which constitute cruel, inhuman or degrading treatment and often amount to torture."

Amnesty said caning violated the UN Convention Against Torture, which Indonesia ratified in 1998, and urged the government to review the bylaw to conform with international and national human rights laws and standards.

Prior to Thursday's caning, 21 men were subjected to the same punishment, also regarding togel, bringing the total this month to 40 people. Amnesty says a total of 16 people were caned in the province last year.