Three Irish men have been sentenced to prison by a Perth court for a roof repair scam targeting the elderly.

In January, John Jason O'Brien (18), Thomas Kiely (19), and Desmond O'Reilly (23) conned elderly people, some aged in their nineties, into believing their roofs needed repair.

The men climbed onto roofs and damaged them, before approaching their victims and offering to "fix" them.

According to ABC news Australia, District Court Judge Laurie Levy described the scam as a "sophisticated scheme to defraud and target elderly people".

He said none of the men were the "driving force" of the scam, as others were also involved.

Mr O'Brien was sentenced to 13 months in jail, while Mr Kiely and Mr O'Reilly both received an eight-month sentence.