Hawke's Bay Regional Prison spent hours in lockdown yesterday after a hoax bomb threat was made - believed to have come from inside the prison.
Police were alerted just before 9.30am yesterday morning about "an item of concern", a spokeswoman said.
Although prison staff were unable to comment, a Corrections spokesman confirmed a bomb threat had been made by telephone.
As police responded to the scene at the prison in Longlands, Hastings, the site went into lockdown. During the morning a white security van blocked the prison entrance and turned cars away.
The lockdown was in place until the early afternoon, with police finishing their investigations just before 2pm, a spokeswoman said.