Jimmy Fallon has apologised to staff at NBC's Tonight Show following allegations that he had created a "toxic" work environment.

"I feel so bad I can't even tell you," he told staff on a Zoom call, according to Rolling Stone magazine.

It follows an investigation by the magazine which exposed damaging allegations from 16 of the US TV show's current and former staff.

They told Rolling Stone that for years they felt belittled and intimidated.

They described Fallon's behaviour as "erratic" - depending on whether he was a having a "good Jimmy day" or a "bad Jimmy day".

They said they were subject to angry "outbursts".

According to Rolling Stone's original story which revealed the allegations, the guests' dressing rooms were referred to as "crying rooms".

"Writing for late night is a lot of people's dream jobs, and they're coming into this and it becomes a nightmare very quickly," an anonymous person told the magazine.

For those who had concerns and expressed them to human resources, the issues remained unresolved, the magazine reported.

All of the current and former staff who spoke to Rolling Stone requested anonymity "out of fear of retaliation".

In a statement, a spokesperson for NBC wrote: "We are incredibly proud of The Tonight Show, and providing a respectful working environment is a top priority... As in any workplace, we have had employees raise issues; those have been investigated and action has been taken where appropriate."

After the Rolling Stone investigation, Fallon reportedly told the show's staff: "It's embarrassing and I feel so bad.

"Sorry if I embarrassed you and your family and friends."

However, some current employees of the show have come to Fallon's defence.

One told People magazine that Fallon was "a really, really positive guy".

"He makes a point of commending you when you do a great job and when he's happy," said the employee, who also requested to remain anonymous. "I've never been belittled, yelled at, nothing like that."

"I'm really happy to work there right now," another employee, who said they had not heard of "crying rooms", told People.

The Tonight Show has had nine different showrunners - top-level TV producers - since Fallon took over as the show's host in 2014.

In its debut with Fallon, the show had over 11 million viewers.

Prior to The Tonight Show, Fallon built his reputation in comedy as the host of NBC's Late Night With Jimmy Fallon.