Andy Gray, the Sky Sports presenter at the centre of a sexism storm following derogatory comments about a female official, has been sacked by the broadcaster in response to "new evidence of unacceptable and offensive behaviour".

Sky Sports' managing director Barney Francis, who yesterday disciplined both Gray and Richard Keys for their comments, said he had "no hesitation" in summarily terminating Gray's contract.

"Andy Gray's contract has been terminated for unacceptable behaviour. After issuing a warning yesterday, we have no hesitation in taking this action after becoming aware of new information today," he said.

Sky said in a statement that the new evidence related to "an off-air incident that took place in December 2010" and "came to light after Andy Gray had already been subjected to disciplinary action for his comments of 22 January 2011".

Sky confirmed that the incident in question is a new YouTube clip that emerged today, that showed Gray making sexist comments to co-presenter Charlotte Jackson before going on air.

Gray, Sky's expert pundit for almost two decades in a long-standing partnership with Keys, was originally suspended yesterday after a Sunday newspaper published a transcript of the pair criticising female match official Sian Massey during Wolverhampton Wanderers' match with Liverpool on Saturday.

The pair discussed Massey's appointment for the game at Molineux on Saturday, speaking when they believed their microphones were switched off. They agreed that female officials "don't know the offside rule", with Keys adding: "I can guarantee you there'll be a big one today. Kenny [Dalglish] will go potty."

Massey was this afternoon stood down from her engagement to run the line tonight at a League Two match between Crewe Alexandra and Bradford City.

Mike Riley, the general manager of Professional Game Match Officials said: "PGMO and Sian believe that with any football match the focus should not be on the officials but on the players and the game itself. That is only fair to those connected with the clubs and their supporters.

"Sian is an excellent professional who has unwittingly found herself in the middle of a story that has nothing to do with her competence as a match official. Sian only wants to be notable for her performance as an assistant referee and is keen for things to get back to normal so she can return to officiating as soon as possible.

"Sian has the full backing of PGMO and we hope she continues her development, which has shown excellent progress so far. It is important for PGMO to have talented people from all backgrounds getting involved in refereeing. The more people are attracted to the game the better standards will be and the more everyone can talk about the football."

Keys went to remark on the newspaper column by the West Ham United vice chair Karren Brady, saying: "The game's gone mad. See charming Karren Brady this morning complaining about sexism? Yeah. Do me a favour, love."

Brady said the comments made her "blood boil" while the England captain Rio Ferdinand labelled them "prehistoric".

Earlier today, a third Sky Sports presenter was taken off air. Andy Burton was shown discussing Massey with Gray ahead of Saturday's match in footage leaked to sister channel Sky News.

Burton said "apparently, a female lino today, bit of a looker", with Gray responding: "A female linesman?"

"He [a Sky Sports crew member] says she [Massey] is all right," Burton continued, "now I don't know if I should trust his judgment on that?"

Gray then said: "No, I wouldn't. I definitely wouldn't ... I can see her from here," before swearing and adding: "What do women know about the offside rule?"

Burton had been due to appear in his role as a touchline reporter on Sky's coverage of tomorrow night's Carling Cup semi-final second leg between Birmingham City and West Ham but will now be replaced.

It is understood that Sky had originally planned to treat Gray's exchange with Burton as part of the same disciplinary charge but the emergence of the new evidence made his position untenable.

The former Everton and Aston Villa player, believed to be on a seven-figure salary and a key component in Sky Sports' growth story over 20 years, recently began legal action against the News of the World – another arm of Rupert Murdoch's empire – over phone hacking allegations.

Betfair, the online betting exchange endorsed by Gray, earlier today condemned the former player's behaviour but said it would not be dropping him from its advertising for now. Gray has been a very visible presence in its latest advertising campaigns.

"Betfair doesn't tolerate sexism, and we expect others who represent our brand to share similar values," said a spokesman. "We've expressed our disappointment to Andy Gray's representatives about the comments that have been reported in the media over the last 48 hours. At present we have no plans to change the way we work with Andy."