Her spokesperson denied the two were dating in early February.
But the latest pictures of Scarlett Johansson and Sean Penn at a restaurant in LA on Tuesday tell a different story.
As the pair were enjoying a lobster dinner together the Iron Man 2 star, 26, was spotted with one of her feet placed on the Oscar winner's lap, 50.
And the following day, the pair jetted to Mexico for a whistle-stop visit, further fuelling rumours of a romance.
They were first linked back in January and were said to have met at a hotel, only weeks after Scarlett's split from husband of two years, Ryan Reynolds.
But her representative denied any romantic involvement, saying the couple had been "friends for years."
Sean, who was once married to Madonna, split from his wife of 14 years, Robin Wright Penn, last August.
Photo: © Getty
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