Brad Pitt’s mother has written a letter to a Missouri newspaper attacking Barack Obama on his support for marriage equality.

Jane Pitt wrote to the Springfield News-Leader to say Christians should back Republican presidential candidate Mitt Romney, who is against abortion and same-sex marriage.

Mrs Pitt wrote: “Any Christian who does not vote or writes in a name is casting a vote for Romney’s opponent, Barack Hussein Obama – a man who sat in Jeremiah Wright’s church for years, did not hold a public ceremony to mark the National Day of Prayer, and is a liberal who supports the killing of unborn babies and same-sex marriage.”

Referring to Romney’s Mormon religion, she added: “Any Christian should spend much time in prayer before refusing to vote for a family man with high morals, business experience, who is against abortion, and shares Christian conviction concerning homosexuality just because he is a Mormon.”

Her views are at odds with those of her Hollywood superstar son, who has been an outspoken advocate for marriage equality.

Several years ago, he and partner Angelina Jolie announced they would not wed until every couple in the US has the right to marry.

The couple confirmed their engagement in April.

In January, Pitt told the Hollywood Reporter that he did not know whether they would be able to go the distance on the promise.

He told the magazine: “We’d actually like to, and it seems to mean more and more to our kids. We made this declaration some time ago that we weren’t going to do it till everyone can. But I don’t think we’ll be able to hold out.

“It means so much to my kids, and they ask a lot. And it means something to me, too, to make that kind of commitment.”