The headquarters of the Quinn Group in Co Fermanagh have been damaged in a fire.
Police said they are treating the blaze at the premises on Ballyconnell Road in Derrylin as suspicious.
The fire comes weeks after a lorry was driven in to the building's canteen.
A spokesman said the blaze was reported shortly before 7pm on Friday, by which time the fire had already caused damage to the building.
Detectives in Enniskillen have appealed for anyone with information to come forward.
The site has been attacked on a number of occasions since former billionaire Sean Quinn lost control of his business empire.
The former tycoon has condemned the attacks and called for an end to the incidents.