Ugly Betty star America Ferrara is the latest Hollywood star to publicly oppose a measure that would ban gay marriage in California.

She has appeared with co-stars Tony Plana and Ana Ortiz on Spanish language TV stations in an advert for No on Prop 8.

The statewide ballot on election day next Thursday seeks to overturn the state Supreme Court’s ruling in May that same-sex couples are legally entitled to marry.

Internet companies Google and Apple, powerhouses of the California economy, have also backed the campaign to defeat Proposition 8.

Brad Pitt and Steven Spielberg have both donated funds to No on Prop 8.

Yesterday California’s senior United States Senator, Dianne Feinstein, appeared in an ad for the group.

“It changes our constitution, eliminates fundamental rights, and treats people differently under the law,” she said.

“We are so moved to have the strong, trusted and independent voice of Senator Feinstein joining the chorus of those voting no on 8,” said No on Prop 8 Campaign Director Patrick Guerriero.

“California voters know that Senator Feinstein speaks from the heart and it matters when she urges voters to reject this unfair initiative.”

Earlier this week Maria Shriver, the wife of Governor of California Arnold Schwarzenegger, publicly expressed her support for same-sex marriage in the state.

Last week a Public Policy Institute of California found Proposition 8 losing 52% to 44% among likely voters.

4% are undecided. In polls taken in August and September by the institute found double digit leads for opponents of the measure.

Proposition 8 would amend the state Constitution to “eliminate right of same-sex couples to marry.”

In May the California Supreme Court overturned a ban on same-sex marriages in the state.

The Court voted 4 to 3 to strike down the ban.

Opponents of gay marriage raised more than a million signatures to place the initiative on the November ballot.