Joaquin Phoenix and Rooney Mara have reportedly welcomed a baby son named River.

The news was revealed at the Zurich Film Festival by director Victor Kossakovsky while promoting his movie Gunda – on which the Oscar-winning star is an executive producer.

Explaining the actor’s absence, he said: “He just got a baby, by the way, his name was… a beautiful son named River, so he cannot promote it [the film] now.”

The name is a touching tribute to Joaquin’s brother, the Stand by Me actor River Phoenix, who died of a drug overdose aged 23 in 1993. The couple are yet to confirm the news, but Joaquin has often discussed the impact of losing his older brother when he was just 19-years-old.

When accepting the Oscar for Best Actor earlier this year, he recited lyrics written by his late brother.

Joaquin, who won for his titular turn in Joker, said: “I’ve been a scoundrel in my life. I’ve been selfish, I’ve been cruel at times, hard to work with.”I’m grateful, so many of you in this room have given me a second chance and I think that’s when we’re at our best, when we support each other, not when we cancel each other out for past mistakes, but when we help each other to grow, when we educate each other, when we guide each other toward redemption. That is the best of humanity.”

“I just want to… when he was 17, my brother wrote this lyric, he said, ‘Run to the rescue with love and peace will follow’.”

It is believed that he met Mara while the pair were working on Spike Jonze’s 2013 movie Her, but first started dating in 2016 after reuniting on the set of biblical epic Mary Magdalene.