Las Vegas Raiders head coach Jon Gruden  Photo: IC

Las Vegas Raiders head coach Jon Gruden resigned on Monday, as new allegations of using misogynistic and anti-gay language rocked the coach just days after he was accused of racism.

Gruden stepped down after meeting Raiders owner Mark Davis earlier Monday soon after fresh revelations engulfed the embattled head coach.

"I love the Raiders and do not want to be a distraction... I'm sorry, I never meant to hurt anyone," Gruden said in a statement on the Raiders website. 

Gruden's bombshell decision comes after a tumultuous 72-hour period that began Friday when the Wall Street Journal revealed the coach had used a racist trope to describe players union chief DeMaurice Smith.

In the email, Gruden referred to Smith as having "lips the size of Michelin tires." The language invokes imagery long used in anti-black caricatures.

The National Football League condemned the email as "appalling, abhorrent and wholly contrary to the NFL's values."

In comments to ESPN at the weekend, Gruden said he was "ashamed" of his language, and insisted he "didn't have a blade of racism" in his character.

But late Monday, The New York Times reported it had reviewed several further emails by Gruden in which he used anti-gay and misogynistic slurs as he disparaged issues such as the emergence of women referees to the drafting of a gay player.

Gruden coaches the only openly gay player in the NFL, Raiders defensive end Carl Nassib, who came out as gay in June.

In other emails reported by the Times, Gruden derided players who protested during the playing of the US national anthem, calling for them to be fired.

Gruden also used anti-gay slurs to abuse NFL Commissioner Roger Goodell over the league's efforts to reduce concussions.

The Times reported that the emails stemmed from a separate workplace misconduct investigation, which did not directly involve Gruden.

In the emails reviewed by the Times, Gruden is alleged to have referred to NFL chief Goodell as a "faggot" and a "clueless anti-football pussy."

He also took aim at Goodell for reportedly leaning on then-St. Louis Rams head coach Jeff Fisher to draft "queers" - a reference to openly gay college player Michael Sam, who was picked by the club in 2014.