PARIS, April 29 (Reuters) - France has foiled a terrorist act and is holding four suspects in custody, said the French interior minister and a police source on Monday. The police source said the four suspects had been arrested on suspicion of acquiring weapons 'with a view to committing a terrorist act.' 'We had sufficient evidence to lead us to believe that a major attack was being planned,' Interior Minister Christophe Castaner also told reporters on Monday. (Reporting by Julie Carriat; Editing by Sudip Kar-Gupta and Alison Williams)