Scarlett JohanssonScarlett JohanssonScarlett Johansson said she nearly crashed her car when she saw her "brontosaurus-sized" boobs on a billboard.

The Lost in Translation actress slammed on the brakes when confronted with a giant advert of herself in Hollywood, according to the Daily Record.

And the 20-year-old hinted that the picture of her chest had been digitally altered to promote new movie, The Island.

She said: "I was driving through Los Angeles and I look up and see the biggest photo of me I have ever seen in my life on a massive ad space.

"I screamed and slammed on the brakes. I couldn't believe it.

"It's very strange to see my cleavage the size of a brontosaurus. My breasts were huge.

"I had long hair and my goodness, I couldn't get past the cleavage."

The Island, in which Scarlett stars alongside Ewan McGregor, has flopped at the US box office.

The pair are portrayed in a nightmare world where human clones are bred to provide spare body parts.

But Scarlett revealed she enjoyed her kissing scenes with the Star Wars hunk.

She said: "I get paid to make out with Ewan McGregor and roll around in bed all day. It's a hard job but somebody has to do it."