Figures obtained exclusively by the Newcastle Herald show that one in four drug tests returned positive last year, the equivalent of three a week.

Yesterday, a team of corrective services officers and a drug detection dog conducted several raids looking

for drugs or evidence of their use in part of the maximum security section of the jail.

As corrections authorities vowed to come down hard on inmates caught with drugs, they conceded it was an uphill battle.

Department of Corrective Services Cessnock and Lower Hunter Cluster general manager David Mumford said large numbers of visitors attempted to traffic drugs into the jail every year.

Mr Mumford said the majority of drugs were smuggled to prisoners by partners, friends and family during contact visits on weekends.

Packages containing drugs and contraband were also regularly buried or hidden around the prison in the hope that work release inmates would smuggle them inside.

He said most inmates who returned positive tests were ‘‘young offenders’’ who were ‘‘always trying to beat the system’’.

Cannabis was the drug most often detected in tests, closely followed by buprenorphine, known as hillbilly heroin.

‘‘It would be very, very hard to provide a normal correctional environment where there are no drugs,’’ Mr Mumford said.

‘‘While ever we have contact visits, inmates will always attempt to have substances trafficked into the centre ... but we will continue to vigorously pursue the matter and improve our statistics.’’

There were 147 failed tests last year and another 16 inmates refused to be tested, regarded in the system as an admission of guilt.

According to the statistics obtained under Government Information Public Access, 28per cent of tests were positive in 2009 and 25per cent in 2010 and last year.

Cessnock jail houses 498 maximum and minimum security inmates.

Mr Mumford said 10per cent of inmates were required to be randomly tested every year.

But he said the Cessnock program had been expanded to include inmates on release programs and targeted testing based on intelligence.

‘‘If we can break the addiction cycle while in custody there is far more chance of surviving temptation on release,’’ he said.

In the year to March 679 tests were conducted, including 225 targeted tests based on officers’ intelligence and 121 of these, or 54per cent, were positive.

‘‘A high proportion of positive results are targets,’’ Mr Mumford said. ‘‘We are doing our job and getting it right.’’

Punishments for failing drug tests include loss of contact visits and privileges. Repeat offenders must enter a management plan and some minimum security inmates face being moved to more secure units.

At Muswellbrook’s minimum security jail, St Heliers, 1224 tests were conducted last year and 98, or 8per cent, were positive.

All of the 77 drug tests carried out at Kariong Juvenile Correctional Centre in the past three years were negative.