Indian police shot dead 20 stone-throwing sandalwood smugglers on Tuesday during the biggest operation for years to stamp out trafficking of the rare commodity, law-enforcement authorities said.

Opposition politicians and human rights activists challenged the report, maintaining that those killed in the incident in the southern state of Andhra Pradesh were only unarmed laborers and calling for an investigation.

Andhra Pradesh Police Chief J.V. Ramudu told reporters that a dozen-strong police task force had come under a hail of stones launched by around 100 stone-throwing smugglers who were also brandishing axes, sickles and other sharp-edged weapons.