It appears that actor Sean Penn is once again married after a friend of the star revealed the big news on social media.

Hollywood icon Penn, 59, has been dating Mortal Engines actress Leila George, 28, since 2016, but ET Canada reports that the pair have since tied the knot in a "secret" ceremony.

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Their secret marriage appeared to be outed by friend Irena Medavoy - who is also the wife of Black Swan producer Mike Medavoy - after she posted a message of congratulations to Instagram.

Medavoy captioned the post: "We are so happy for @leilageorge #seanpenn getting married.

"We love you. Thank you for being like family a son to mike we are over the moon to find your soul mate true partner @coreresponse true love that also changes the world for better.

"You are meant to be together God Bless you both and the family you have joined. Introducing the Penn’s #marriage."

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However, it seems the newlyweds may have been keen to be the ones to announce their nuptials to the world, as Medavoy has since deleted the post (awkward).

And in a now-deleted Instagram story, Medavoy also shared a snap of what looks like Penn and George's wedding bands, captioning the snap: "Congratulations we love you".

Per The Mirror, Leila the daughter of Jurassic World star Vincent D'Onofrio - who is just one year older than Penn.

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Fans of Penn will remember that he was previously married to pop legend Madonna and actress Robin Wright. He has two children with Wright, born in 1991 and 1993.

And according to news.com.au, the actor has also been romantically linked to Charlize Theron, Susan Sarandon, and Downton Abbey star Elizabeth McGovern.

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Both Penn and George are yet to make any public announcement regarding any marriage - but after Medavoy let the world know, we can only imagine it is a matter of time.

But, for now, congratulations to the happy couple!

Sean Penn, 59, 'marries' Leila George, 28, in 'secret' ceremony