Oscar-winning actor Sean Penn has said that his film Milk is “one of the steps forward” in the battle for gay marriage.

Mr Penn won the Academy Award for his portrayal of Harvey Milk, the first openly-gay man elected to public office in the United States.

Mr Milk was assassinated less than a year after his election to the San Francisco Board of Supervisors in 1977.

During his acceptance speech at last week’s ceremony Mr Penn spoke about gay marriage.

In November voters in California approved a ballot measure denying gay and lesbian couples the right to marry.

Proposition 8 was in response to a court ruling that gay marriage was legal.

Between June and November 18,000 same-sex couples got married in California.

The validity of Prop 8 is being challenged in the state Supreme Court.

Mr Penn said he hoped Milk would change attitudes towards same-sex marriage.

Now he has revealed he wants to take his film to the country’s President.

“Eventually we are hoping for a White House screening,” he said.

“I think this film will be one of the steps forward … but I think things are going to go forward with or without it.

“I was once asked to tell the difference between luxury and necessity for a human being.

“The right to equality for all, including homosexuals, is of course a necessity.

“That’s why this right will become a reality and I think in its own way this film will be part of that.

“The need for tolerance, equality and so on is on the move, and will go on.”

President Obama supports civil unions but not same-sex marriage.

On Thursday the California Supreme Court will hear arguments about the validity of Prop 8.