Scarlett Johansson and Sean Penn Split

By Oliver Jones

UPDATED 06/03/2011 at 07:00 AM EDT • Originally published 06/02/2011 at 08:00 PM EDT

Scarlett Johansson and Sean Penn are no longer dating, a source tells PEOPLE.

Speculation about the pair began after Johansson did not attend the Cannes Film Festival with Penn for his movie The Tree of Life. She has been working on The Avengers in New Mexico, reprising her role of Black Widow from Iron Man 2.

Johansson, 26, and Penn, 50, made headlines when they took a whirlwind trip to Cabo San Lucas after being spotted getting flirty together during a lunch date in Los Angeles.

The pair attended a White House Correspondents' Dinner party in Washington D.C. in April and had been spotted in a series of cozy outings in L.A.



The reason for the split wasn't immediately known. Reps declined to comment.