Carl Froch has apologised for threatening to "kill" Mikkel Kessler in their IBF super-middleweight fight in London on Saturday night - but will still face an investigation by the British Boxing Board of Control.

Froch took to Twitter today to say: "I'm sorry if my comments yesterday offended anyone. This fight means so much to me & emotions are running high. See you at the weigh-in."

The Board's general secretary Robert Smith said the governing body would look into the comments, telling the Press Association: "Carl's comments are inappropriate and we are disappointed in them."

Froch and Kessler have been friends since their first bout three years ago, which Kessler won on points in Denmark, but Froch's desire for a revenge win led him to change tune and launch a vicious attack.

Froch told reporters: "On Saturday night, if I have to, I will kill this f****r.

"Sorry about the language, but I will kill him. It sounds brutal, it sounds horrible, but this is what it means to me.

"I'm going to leave it in the ring. And when I'm smashing his face in, I am going to go for the kill. I am going to go for the finish."

While boxing history is littered with similarly ill-advised comments, Smith said he was particularly disappointed to see them come from a fighter like Froch.

Smith said: "They are very uncharacteristic from Carl, who is usually a very well-behaved and measured young man.

"We are surprised and disappointed in his comments, however I have spoken to his management team of Rob McCracken and Eddie Hearn and we are looking into it and will deal with it accordingly.

"Carl is licensed by the Midlands Area Council and they will deal with it as quickly as they possibly can. Obviously we are not in a position to do anything about it before the fight." 

Smith acknowledged Froch's difficult mindset in the days before what is arguably the biggest fight of his career, but stressed it is no excuse for breaking one of the sport's unwritten rules.

Smith added: "This is Carl's biggest fight of his career - if he wins this he carries on and if he loses what does he do? It is a difficult time two or three days before the fight and he is right on edge.

"But being highly strung at the moment is no excuse. Carl is a decent young man and he is well aware that he shouldn't have said it.

"Up until now all the publicity surrounding the fight has been superb and this has dampened it somewhat."