Sean Penn is currently under fire following an offensive joke he made at the expense of Alejandro González Iñárritu at the Oscars.

Penn took the stage at the end of Sunday's 87th Annual Academy Awards to announce the Best Film award, Daily Mail reports. Before announcing Mexican-born Iñárritu's "Birdman" as the winner, Penn remarked, "Who gave this son of a b*tch his green card?"

The term 'green card' refers to the document issuing "permanent residency to immigrants in the United States," Daily Mail wrote. 

A lot of people, particularly on Twitter, expressed their distaste for the actor's statement. Cosmopolitan Magazine posted: "It doesn't matter if Sean Penn was joking, his green card comment at the Oscars was awful," while immigration activist Jose Antonio Vargas called the actor's joke "plain xenophobic."

Mario Lopez of "Extra" tweeted that Penn ruined "a fantastic moment," pointing out that no one questioned the immigration status of the dozens of Australian and British actors also present in the event, Daily Mail wrote. Penn's remark also further fueled the controversy surrounding this year's Oscars about the lack of diversity in the list of nominees.

Iñárritu, however, backed his pal's remark, stating that he and Penn have been good friends since they worked together in 2003's "21 Grams," the news outlet noted.

"I found it hilarious," Iñárritu said after the ceremony, as quoted by Daily Mail. "Sean and I have that kind of brutal (relationship) where only true friendship can survive."

The filmmaker, who won three Oscars during Sunday's ceremony, insisted that he also made jokes at Penn's expense in the past.

"I make on him a lot of very tough jokes that I will not tell you (sic)," Iñárritu added, who also quipped that the Academy of Motion Picture Arts and Sciences might introduce a residency requirement.

"Maybe next year, the government will inflict some immigration rules (on) the academy. Two Mexicans in a row, that's suspicious, I guess," the director said, as quoted by Daily Mail.

Iñárritu dedicated the Oscar win to his fellow Mexicans residing in his home country, saying, "'I pray that we can find and build the government that we deserve. And the ones that live in this country who are part of the latest generation of immigrants in this country, I just pray that they can be treated with the same dignity and the respect of the ones who came before and (built) this incredible immigrant nation."

The film, which stars Michael Keaton, also went home with the Best Original Screenplay award. Iñarritu wrote the movie alongside Nicolás Giacobone, Alexander Dinelaris, Jr., and Armando Bo. Emmanuel Lubezki (also a Mexican) who won Best Cinematography for his work in the movie, Variety reports.