MrBeast says he's hired investigators after his former co-host was accused of grooming a teenager.

Ava Kris Tyson was accused by other YouTubers of sending inappropriate messages to the minor when she was 20.

The 28-year-old, who'd worked on MrBeast's channel since 2012, strenuously denied grooming but said the pair had "mutually agreed" she should quit.

In a follow-up statement, MrBeast, real name Jimmy Donaldson, said he was "disgusted" by the "serious allegations of Ava Tyson's behaviour online".

Ava has apologised for "past behaviour" which was "not acceptable".

MrBeast is the world's biggest YouTuber with more than 300m subscribers.

He said he had become aware of the allegations against Ava, which first started circulating online last month, "over the last few days".

"I am disgusted and opposed to such unacceptable acts," he says.

MrBeast's statement said he had "been focused on hiring an independent third party to conduct a thorough investigation to ensure I have all the facts".

"That said," he continued, "I've seen enough online and taken immediate action to remove Ava from the company, my channel, and any association with MrBeast.

"I do not condone or support any of the inappropriate actions."

The US YouTuber added that he would wait for the investigators to finish their work and "take any further actions based on their findings".