Manchester United [ Images ] manager Alex Ferguson [ Images ] was charged with improper conduct by the Football Association on Thursday for comments about referee Martin Atkinson after his side's 2-1 defeat at Chelsea [ Images ] this week.

"The charge relates to comments made about match official Martin Atkinson in post-match interviews following Manchester United's fixture with Chelsea at Stamford Bridge [ Images ] on Tuesday," the FA said on its website (www.thefa.com).

Ferguson criticised Atkinson after Chelsea came from behind to win the game with a Frank Lampard [ Images ] penalty awarded after Chris Smalling was ruled to have tripped Yuri Zhirkov.

Fergsuon was also angry that Chelsea's Brazilian defender David Luiz, who volleyed the equaliser, escaped a red card after a second-half challenge on Wayne Rooney [ Images ].

"It was a major game for both clubs and you want a fair referee," Ferguson said in an interview after the game. "You want a strong referee anyway and we didn't get that.

"I don't know why he's got the game. I must tell you, I must say that when I saw who was refereeing, I feared the worst."

The defeat, United's second in the Premier League this season, blew the title race wide open with Ferguson's side still four points above Arsenal [ Images ] who now have a game in hand.

Ferguson has until March 8 to respond to the charge.