WASHINGTON - Gwyneth Paltrow lent a touch of Hollywood glamour Wednesday to a campaign against legislation that would prevent the labelling of genetically modified food in the United States.

The Oscar-winning actress and mother of two appeared on Capitol Hill alongside Democratic senators opposed to the so-called Safe and Accurate Food Labeling Act.

Nicknamed the Denying Americans the Right-to-Know Act, or DARK Act, by its opponents, the bill is pending Senate action after clearing the Republican-controlled House of Representatives.

"I'm not here as an expert," said Paltrow, who runs a lifestyle blog called Goop when not starring in films such as "Shakespeare in Love" and "Iron Man."

"I'm here as an American mother who honestly believes that I have the right to know what's in the food I feed my family," she said.

"There is so much that has not yet been proven" about the safety of genetically modified (GMO) food, added Paltrow's mother, actress Blythe Danner, who also participated in Wednesday's media event.

Paltrow is among a number of celebrities who have endorsed the Just Label It campaign that is aiming to derail the legislation.

The campaign says that 90 percent of Americans surveyed in opinion polls favor labelling GMO foods and that more than 200,000 people have signed its online petition against the DARK Act so far.

If enacted, Just Label It says the legislation would "virtually eliminate" the ability of the Food and Drug Administration to come up with a nationwide GMO labelling system.

It would also preempt the ability of states to set up their own GMO labelling regimes, as Vermont plans to do next year.

"Every American in this great country has the right to know if the food they eat was created in a lab," said Senator Jon Tester, a Democrat and farmer in Montana, his home state.

GMO labelling is currently required in 64 countries, according to Just Label It, including Australia, Brazil, China, Russia and the 28 member states of the European Union.

But the Coalition for Safe and Affordable Food, a food industry group, says GMO labelling in the United States would create "consumer confusion" and jack up grocery bills by as much as $500 a year per family.

It also mocked Paltrow personally, dismissing her as another in a series of "out of touch Hollywood celebrities" who want to "enshrine their lifestyle choices" on everyday American families.

"We are confident the Senate will stand with science and American facilities rather than the extreme agendas of Hollywood elites," it said in a statement.