"It is alleged that comments made by the head coach during a post-match interview constitute improper conduct as they were personally offensive to the match official and/or bring the game into disrepute contrary to FA Rule E3.1."

Nuno has until January 5 to respond to the charge, the FA said.

The Wolves boss said about Mason after the match: "The referee does not have the quality to whistle a game in the Premier League.

"It is not about the crucial mistakes or decisions, it is about the way he handles the game. The players get nervous, too much voices, he whistles by the voices when some players are shouting.

"We are talking about the best competition and clearly he doesn't have the quality to whistle the game. I'm very disappointed to say this but I would not feel right if I didn't say it.

"I just don't want to see him more – that's what I told him. I hope he doesn't whistle a game of ours again because all the games we have with Lee Mason are always the same.

"He cannot control the players, the players are constantly arguing – both teams. With all the other referees the game flows, there's dialogue. He's just not ready to do it."

On December 23, Nuno said he would be discussing the matter with the FA on December 29 and that he would only apologise for the timing of his comments.

Nuno said: "They were not in the best moment to come across because it could be a bad interpretation.

"For that I will apologise on my timing, but I won't apologise for my words and thoughts.

"I never ever will judge or question the integrity of a referee. I never did it and I will never do it in my life.

"What I said is about the ability of the referee, what I felt and what I saw in the match and previous matches."

Post-match comments about a referee's performance are permitted under FA regulations provided they do not imply bias, attack an official's integrity, are not personally offensive, prolonged or particularly unreasonable.