A group of six prisoners have climbed onto the roof of Hawke's Bay Regional Prison.

It's understood the youth unit inmates scaled part of the building in their ascent about 2.30pm.

Liz Hawthorn, Lower North Regional Commissioner, said staff responded "immediately to contain the incident" and were currently talking to the prisoners.

"All other prisoners in the Youth Unit have been safely secured," Hawthorn said.

"The area is within the secure perimeter of the prison's unit. There is no threat to the wider security of the prison and no threat to public safety."

A police spokeswoman confirmed police were aware of an incident at the prison, but have not been called in and could not give further detail.

In July 2011 a protest at the prison was sparked after an inmate persuaded 11 other prisoners to protest his reclassification with him.

In July 2011 inmates (pictured) made headlines after a rooftop protest at Hawke's Bay Prison. Photo / NZME

Seven of those were detained by guards overnight with five remaining protesters making their way onto the roof via the ceiling cavity.

One prisoner surrendered about midday, and the other four remained in what amounted to a 23-hour rooftop standoff.