Scarlett Johansson and Gwyneth Paltrow became friends on the set of 'Iron Man 2'.

The actress - who plays Russian spy Black Widow in the Marvel superhero movie - says it was great having another woman to bond with on a mostly male set.

She said: "I've always admired her work and we've both in the industry for a long time, so we shared that. We both know a lot of the same people. I also think she was relieved. She was like, 'A woman, my God! You don't know what I've been dealing with!' And I looked over at Robert Downey Jr. and Jon Favreau slapping each other in the corner!

"We didn't want our characters' relationship to be catty. I think Gwyneth's character is bewildered by mine and my character isn't really concerned with hers, which is interesting."

Scarlett took on a complex exercise regime and gruelling diet plan to fit into the skin-tight Lycra catsuit she had to wear for the role, and Gwyneth - who plays Pepper Potts, the assistant of Robert's character Tony Stark in the film - gave her numerous cooking tips to stay trim.

She added to Stylist magazine: "I had to cook more than normal, because I was working and eating in such a clean way, so we shared tips on how to make things more delicious when they're not that delicious."

The 25-year-old actress completed many of her own stunts and fight scenes for the film and admits the all-action role took its toll on her body.

She said: "I spent so many hours low to the ground and squatting. I couldn't walk for three days after those, it was horrible."