Fewer prisoners are using drugs in jail, as shown in the latest data released by the government.

Corrections Minister Judith Collins says positive drug tests among prisoners are at an all-time low.

There were more than 4500 random drug tests on inmates last year.

Just 3% returned positive results, down from 10% five years ago.

At the start of the millennium almost a quarter of random drug tests in jail were positive.

Since then corrections officers have been given more legal power to search inmates and their property.

Prison security has been stepped up and visitors are also subject to greater scrutiny.