The deal will see Gaymers, Blackthorn and Olde English cider brands become part of C&C Group's UK portfolio.
John Dunsmore, C&C chief executive, said: ‘This transaction strengthens our position within the world's largest cider market and broadens the scope of the group's existing cider offering.'
After a strong debut in the UK market in 2005, Magners, the original over ice premium cider, has struggled against competition from Scottish & Newcastle's Bulmers Original and Gaymers.
The transaction should be complete by mid-January 2010, subject to Office of Fair Trading approval.