US late night host Jimmy Fallon has apologised after video resurfaced of him wearing blackface during a Saturday Night Live (SNL) sketch.

The performer wore dark makeup in the scene, where he portrayed comedian and SNL alumni Chris Rock appearing on a talk show.

Fallon tweeted: “In 2000, while on SNL, I made a terrible decision to do an impersonation of Chris Rock while in blackface.

“There is no excuse for this.

“I am very sorry for making this unquestionably offensive decision and thank all of you for holding me accountable.”

Fallon appeared on SNL from 1998 until 2004, leaving the show to pursue film roles which led to him becoming the sixth permanent host of The Tonight Show in 2014.

US media began reporting last February the existence of footage showing Fallon in blackface, but criticism of the star grew on Tuesday when the clip emerged on Twitter.

The hashtag #jimmyfallonisoverparty quickly gained momentum on the platform, with Fallon later releasing a statement.

SNL has an established history of casting non-black actors in black roles, with Billy Crystal playing Sammy Davis Jr in 1984 and more recently former US president Barack Obama portrayed by Fred Armisen.

Other entertainers to have been criticised for wearing blackface include Robert Downey Jr and comedian Sarah Silverman, while Fallon’s fellow late night host Jimmy Kimmel has also been slammed for wearing makeup to impersonate Oprah Winfrey.

The practice is widely seen as a racist caricature of black people, with Canadian Prime Minister Justin Trudeau’s re-election campaign nearly derailed last year by disclosures that he had darkened his skin for a party in his university days.