Marvel star Mark Ruffalo has criticised talk show host Ellen DeGeneres for her friendship with former US president George W Bush.

DeGeneres, one of the most high-profile LGBTQ figures in America, sparked a backlash after being pictured sitting next to Mr Bush at an NFL game.

Mr Bush, a Republican president, opposed gay marriage while in office. DeGeneres defended their relationship, saying it was important to be friends with people of opposing political views.

She said: “When I say, ‘Be kind to one another,’ I don’t only mean the people that think the same way that you do. I mean be kind to everyone. Doesn’t matter (who).”

DeGeneres was praised for her stance by celebrities including Jamie Foxx and Reese Witherspoon, but Ruffalo refused to join in.

Instead Ruffalo, who plays the Incredible Hulk in films including Avengers: Endgame and Thor: Ragnarok, criticised Mr Bush for leading his country into war in the Middle East.

He tweeted: “Sorry, until George W. Bush is brought to justice for the crimes of the Iraq War, (including American-lead torture, Iraqi deaths & displacement, and the deep scars—emotional & otherwise—inflicted on our military that served his folly), we can’t even begin to talk about kindness.”

The tweet quickly went viral. Twitter users were divided, with some praising Ruffalo and agreeing with him while others vehemently disagreed.

A supporter said: “Thank you @MarkRuffalo for making it clear that if we ever want to live in a world with true kindness that we won’t get there by normalizing war criminals.”

A man identifying himself as a military veteran disagreed with Ruffalo, telling him: “Sorry to interrupt your ‘hulk smash’ moment I served with soo many that did soo much more than me, and we would do it ALL over again for our country! You don’t get to speak for Veterans.”

Ruffalo, a three-time Academy Award nominee, is well-known for his liberal political leanings.

He hit the headlines last month after criticising UK Prime Minister Boris Johnson for comparing himself to the Incredible Hulk while discussing his stance on Brexit.

Ruffalo said: “Boris Johnson forgets that the Hulk only fights for the good of the whole. Mad and strong can also be dense and destructive.”