An inmate at Victoria’s highest-security prison has surrendered to police after threatening to explode a makeshift bomb.

The 44-year-old inmate is believed to have been arrested at approximately 11:30am after making threats to set himself on fire.

Victoria Police Bomb Squad responded to the threat at Barwon Prison near Geelong at approximately 9:30am on Friday.

The man has now been returned to custody at the maximum security prison.

The Victorian Corrections Department said there was no threat to staff or other prisoners.

Authorities had tried to establish a no-fly zone above the prison, Fairfax Media reports.

The man may have unfurled an Irish Republican Army flag during the standoff, Fairfax Radio 3AW reports.

This is the second time in less than eight months that ground match heads have been used to manufacture explosives at the maximum security prison. In July, a small explosion was caused in the high security wing of the jail by a similar device.