Kristen Stewart's history-making trip to the French Oscars was ruined by a broken earpiece.

The Twilight star became the first U.S. actress to win a prestigious Cesar Award when she picked up the Best Supporting Actress trophy for her role in Clouds of Sils Maria at the ceremony in Paris on 20 February (15), but she admits the ceremony was long and confusing.

Stewart briefly had someone translating for her through an earpiece, but when that broke, she went into a "meditative state" to get through the nerve-wracking night.

She says, "It was, like, a four-and-a-half hour show, or something, and they don't have commercials over in France the way that we do, so we didn't even get to take a break and, like, chat and go to the bathroom and get a drink.

"I had a little earpiece for 30 minutes and then it stopped working... I didn't even know when the category came up that it was mine. I had fallen asleep with my eyes open, basically, and then co-star Juliette (Binoche) just screamed in my ear and said, 'You won!'"

And it appears Stewart made a faux-pas as she awkwardly accepted her Cesar, asking a presenter to place the honour on the podium in front of her, rather than hand it to her.

She tells TV chat show host Conan O'Brien, "I think I upset him, honestly. I was pretty nervous. It was kind of a big deal... I could not open my hands up. I was atrophied completely, which is embarrassing and ridiculous... I p**sed him off."