Coimbatore Central Prison officials seized 16 packets of ganja, weighing nearly 1.5 kg, of which 11 were thrown into the premises across the compound wall from Dr. Balasundaram Road, on Thursday night.
Five packets were found near the wall outside the premises.
During night patrol, Assistant Jailor Palanisamy and Warder Ganesan found 11 packets of ganja packed in a bundle near the prison factory inside the premises.
On Friday morning, a special team with dog squad carried out search operations outside the premises and found five packets near the prison wall.
Superintendent of Prison A. Murugesan said that all the packets were thrown into the premises of which five fell outside. To prevent further incidents, trees would be trimmed to a certain level and the grass and lawns near the wall would be cut, he added. The police have registered a case with the Race Course police.