Rufus Wainwright is to wed his long-term partner Jorn Weisbrodt on Thursday.

The 39-year-old singer and the German-born theatre producer -- who got engaged in November 2010 - are to tie the knot at the home of his singer/songwriter father Loudon Wainwright III  and late mother Kate McGarrigle in Montauk, New York, after same-sex marriage was made legal in the state in July 2011.

Sources told the New York Post newspaper that Yoko Ono and Carrie Fisher -- who is best known for playing Princess Leia in the original 'Star Wars' trilogy in the late 70s and early 80s -- are both due to attend the 'Hallelujah' hitmaker's nuptials, along with around 250 guests.

Attendees will be treated to a lunch of champagne and lobster rolls at a local restaurant before heading to Montauk's Shagwong Restaurant -- which Rufus once described as being "filthy and smelly and, once again, sexy" -- for a reception which is expected to go on until 4am.

Rufus is believed to be going to sing at the party along with a number of other live performers instead of a DJ.

The couple raise 18-month-old daughter Viva Katherine Wainwright Cohen -- who Rufus had with Lorca Cohen, the daughter of Leonard Cohen -- along with the youngster's mother.

Rufus -- who has been dating Jorn for more than five years -- proposed at a restaurant in London in November 2010 while the pair were enjoying an Indian meal.