POLICE are tracing two people who were in a car outside Phuket Prison yesterday when two grams of illegal methamphetamine was thrown over the high outer wall.

The Commander of Phuket Prison, Rapin Nichanon, said a prison security patrol spotted a man and a woman behaving suspiciously in the light-colored Toyota Vios saloon about 3pm and the drug - ya ice - was found on the inside soon after.

As a result of the couple's activities, anyone entering the Phuket Prison car park from now on will be issued with a pass after having their identity noted.

Scores of mobile telephones have been tossed over the wall in the past couple of months but Commander Rapin says the telephones are always collected before inmates leave their cells each day.

''We are confident there is no business being conducted from inside the prison,'' Commander Rapin said today. Other prisons in Thailand have detected drugs kingpins continuing to operate on the inside.

Phuket Prison has close to 1400 prisoners in a facility built for 800. More than 100 rai has been set aside in Phuket's east for a new jail, but funding has yet to be approved.