Natalie Portman, fiancé back gay marriage group

Natalie Portman and her fiancé Benjamin Millepied have publicly offered their support for same-sex marriage by backing Freedom To Marry's Say, 'I Do' campaign.

The couple, who announced their engagement and the Thor star's pregnancy in December 2010, have signed a letter calling on US President Barack Obama to advocate equal marriage rights for every American.

"Natalie Portman and her fiancé, Benjamin Millepied, are in love, and believe all loving couples should be able to share in the freedom to marry without discrimination," read an official statement from Freedom to Marry.

"That is why they are joining the more than 100,000 people on Freedom to Marry's Say, 'I Do' Open Letter calling on President to do the right think and become part of America's majority for marriage. (sic)"

Oscar nominee Anne Hathaway, Glee's Jane Lynch, Martin Sheen and Ellen DeGeneres are among other celebrities to have backed the organisation's public appeal.

Freedom To Marry was founded in 2003 by civil rights advocate Evan Wolfson in order to garner support from politicians and their constituents to overturn the US's same sex marriage ban.

Portman recently revealed that she will retire from acting at a young age in order to devote her time fully to raising a child.

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