DUBLIN — The longtime chief of the outlawed Irish Republican Army has been sentenced to 18 months in prison for tax evasion after police found a fortune in fuel-smuggling proceeds hidden on his border farm.

Thomas “Slab” Murphy received the punishment Friday following his December conviction for failing to file tax returns. Ireland’s Criminal Assets Bureau continues to pursue him following the police’s 2006 discovery of piles of cash and checks in hay bales.

The 66-year-old Murphy appeared at Dublin’s anti-terrorist court, a three-judge panel that hears IRA-related cases without a jury, shortly after henchmen stopped Irish journalists from photographing Murphy as he voted in Ireland’s general election.

Dublin civil juries in 1987 and 1998 ruled that Murphy was an IRA commander. He has never previously been convicted on any criminal charge.