Scarlett Johansson dating Sean Penn?

The 26-year-old actress is said to be “smitten” with the 50-year-old actor after hooking up with him in January while she was staying at Los Angeles’ Chateau Marmont hotel while she filmed ‘We Bought a Zoo’ with Matt Damon.

A source told the new issue of Us Weekly magazine: "Their first hook-up was in Scarlett's Bungalow. she is smitten with him."

Scarlett – who split from husband Ryan Reynolds in December after two years of marriage – and Sean began their friendship when she was planning to fly out to Haiti to help people affected by the two earthquakes in January 2010.

The source added: "Scarlett first reached out to Sean when she was planning to visit Haiti with Oxfam. she knew Sean was living there in a tent and turned to him for advice."

Although she didn’t end up going on the trip she and the ‘Milk’ star – who is spending most of his free time on the Caribbean island, where he has been undertaking charity work since the disaster – are said to have developed feelings for each other.

Sean was previously married to Madonna, while his divorce from actress Robin Wright – mother of his two children Dylan, 19, and Hopper, 17 – was finalised in July after 14 years of marriage.