An Auckland college after-ball party turned into an alcohol-free event after the intervention of police and liquor authorities overnight.

Pakuranga College students had paid $55 for the party, which followed the annual school ball.

But when they arrived at the venue, a vacant warehouse in Onehunga, they found Manukau District Licensing Agency inspector Paul Radich had prevented organisers from taking any alcohol inside, the New Zealand Herald reported.

A van which was carrying alcohol was at the warehouse about 30 minutes before the buses were due to arrive but was sent away. It returned to park opposite the warehouse shortly after the party was due to start but Mr Radich got it to leave.

Police Minister Judith Collins said she was delighted with the intervention.