Jon Gruden has resigned as head coach of the Las Vegas Raiders after an investigation into another NFL team revealed numerous offensive emails he sent while working as a television analyst before returning to the coaching ranks. 

NFL Network first reported Gruden was out in Las Vegas approximately one hour after the New York Times released a story quoting from a trove of emails from the coach's personal account that included multiple racist, homophobic and sexist remarks. 

Gruden released a statement confirming his exit and saying he never meant to hurt anyone. The statement read: "I have resigned as head coach of the Las Vegas Raiders. I love the Raiders and do not want to be a distraction. Thank you to all the players, coaches, staff, and fans of Raider Nation. I’m sorry, I never meant to hurt anyone."

Raiders owner Mark Davis also released a statement, saying only that he had accepted Gruden's resignation. 

NFL Network and ESPN reported Gruden and Davis met at the team's facility Monday to discuss the matter and the coach tendered his resignation. 

Assistant head coach and special teams coordinator Rich Bisaccia will take over as interim head coach, the team said. 

The emails, which were sent between 2011 and 2018 while Gruden was an analyst for ESPN, surfaced as part of the NFL's investigation into workplace misconduct allegations at the Washington Football Team. 

Gruden's brother Jay was head coach in Washington from 2014-19, and Gruden's ties with then-Washington team president Bruce Allen date back to his first stint as Raiders coach from 1998 to 2001, when Allen worked in the team's front office. 

Gruden left ESPN and returned to the Raiders in January 2018, going 22-31 including a 3-2 record so far this season. 

According to the emails quoted by the Times, Gruden used homophobic slurs in deriding NFL commissioner Roger Goodell, who he also criticised for introducing female officials to the game. 

The Times report came three days after the Wall Street Journal revealed a 2011 email in which Gruden wrote that NFL Players' Association executive director De Maurice Smith had "lips the size of michellin tires".

An NFL spokesman called those remarks "appalling, abhorrent and wholly contrary to the NFL's values" and Davis released a statement saying the remarks were "disturbing and not what the Raiders stand for".

Gruden apologised, saying he was "ashamed" and "embarrassed" but did not intend his words to be a racial slur. 

The 58-year-old is 117-111 as an NFL head coach, leading the Tampa Bay Buccaneers to a Super Bowl title in 2002.