Three prisoners scaled the roof of a maximum security prison this afternoon, sparking a three-hour standoff with police.

The men were first seen on the roof of Port Phillip Prison about 3pm.

Prisoners on the roof of Port Phillip Prison on Thursday afternoon. Credit:Nine News

They were armed with what appeared to be metal poles, which they were throwing in the direction of police officers on the ground.

About 6pm, the men came down from the roof one by one, where they were handcuffed and escorted away by officers.