Robert Downey Jr's star-studded birthday

Apr 7, 2009, 9:25 GMT

The \'Iron Man\' actor invited Gwyneth Paltrow and her husband Chris Martin, Reese Witherspoon and her partner Jake Gyllenhaal, Ben Stiller and his wife Christine Taylor, Jon Favreau, Sting and his wife Trudie Styler to help him celebrate turning 44 at the Thompson Beverly Hills Hotel on Saturday (04.04.09). © David Gabber / PR Photos

Robert Downey Jr. has thrown a star-studded birthday party.

The 'Iron Man' actor invited Gwyneth Paltrow and her husband Chris Martin, Reese Witherspoon and her partner Jake Gyllenhaal, Ben Stiller and his wife Christine Taylor, Jon Favreau, Sting and his wife Trudie Styler to help him celebrate turning 44 at the Thompson Beverly Hills Hotel on Saturday (04.04.09).

One of the 75 guests told People magazine: "Gwyneth and Jake talked for a while about an upcoming project. Jake and Reese looked very in love. They were being super affectionate, holding hands as they sipped on glasses of wine. They laughed a lot!"

The guests ate sushi platters of spicy tuna, shrimp and sun-dried tomato avocado rolls followed by individual chocolate cakes.

At the end of the night, the guests sang 'Happy Birthday' to Robert before toasting him with sake, an alcoholic Japanese drink.

Gwyneth and Coldplay frontman Chris rubbished all rumours of difficulties in their relationship by spending the evening laughing together.

The source added: "Gwyneth and Chris arrived and left together. And they looked very happy, you could really tell they are content with each other."

Despite marriage claims, Reese was not sporting an engagement ring but spent the night by Jake's side.

A source said: "They looked so in love, and were really affectionate the entire night."