Alejandro González Iñárritu found Sean Penn's ''green card'' joke at last night's (22.02.15) Academy Awards to be ''hilarious''.

Penn presented the 'Birdman' director with the prize for Best Picture at the star-studded event in Los Angeles, but sparked controversy by referring to Iñárritu's Mexican heritage in his speech.

The Hollywood star - who worked alongside Iñárritu on the 2003 film '21 Grams' - joked: ''Who gave this son of a bi***h his green card?''

And while some TV viewers took offence to the remark, Iñárritu found it funny and says it's typical of their friendship.

Speaking to Variety, Iñárritu explained: ''Sean and I had that kind of brutal relationship where only true friendship can survive.

''When I was directing him in 21 Grams, he was always making jokes ... I made a lot of very tough jokes (to him) that I will not tell you.

''I didn't find it offensive, I thought it was very funny.''

'Birdman' fought off stiff competition from Richard Linklater's 'Boyhood' - which was filmed over a twelve-year period - to win Best Picture and Best Director at the Dolby Theater in Los Angeles.

The comedy drama movie also won the Best Cinematography and Best Original Screenplay prizes at the prestigious event.