Mary-Kate Olsen is reportedly dating Nicolas Sarkozy's brother.

The fashion designer is said to be smitten with Olivier Sarkozy - the younger half-sibling of the former French president - after romancing him for over a month. According to the New York Post, the pair are "head over heels" for one another and spent Memorial Day weekend together in the exclusive Hamptons resort near New York.

Mary-Kate, 25, previously dated artist Nate Lowman for over two years before splitting in 2010, while 42-year-old Olivier romanced actress Stella Schnabel for a year before their break-up in March. Olivier was previously married to wife Charlotte and they have two children together.

Last year, Mary-Kate - who shot to fame as a child star alongside twin sister Ashley - was linked to shoe designer Seth Campbell but their romance soon fizzled out. Before embarking on a relationship with previous boyfriend Nate in 2008, Mary-Kate was linked to a string of men - including the late actor Heath Ledger - but had been officially single since 2005 when she split from Greek shipping heir Stavros Niarchos.