Image caption Vincent Lewis' offending led to him being branded "an evil monk".

A 91-year-old former monk, jailed for sexually abusing three boys, is to have his sentence increased by 18 months, the Court of Appeal has ruled.

Judges backed claims that the 10-and-a-half years term, originally imposed on Vincent Lewis for subjecting his young victims to a "shocking" series of attacks, was unduly lenient.

Lord Chief Justice Sir Declan Morgan ordered him to serve 12 years instead.

He highlighted the damage caused by the decade-long campaign of molestation.

"The effect on the victims was horrendous," said Sir Declan.

Lewis, formerly Brother Ambrose of Our Lady of Bethlehem Monastery in Portglenone, County Antrim, admitted more than 50 offences committed between 1973 and 1983.

Image copyright Kenneth Allen, Geograph Image caption Lewis was a former monk at Our Lady of Bethlehem Abbey in Portglenone

He abused one boy while still a monk, and targeted the others after marrying and moving to Annagher Road in Coalisland, County Tyrone.

Some of the attacks were carried out at Portglenone Abbey, where his main responsibility involved operating the printing press.

He also took one victim to isolated woods along the river where he had prepared a private place to carry out further assaults.

The scale of Lewis's offending led to him being branded "an evil monk".

Based on the extent of Lewis's sexual offending, Sir Declan held that a starting point in excess of 20 years was appropriate before allowing discount for his age and other mitigating factors.

He confirmed: "We are satisfied that the sentence imposed was unduly lenient and we substitute for the commensurate sentence of 10 years, six months a sentence of 12 years."