Middlesbrough head coach Aitor Karanka has revealed a difference in opinion is the reason behind Craig Hignett’s surprise departure from the club.

Karanka has also apologised for his actions at the end of Saturday’s 1-1 draw with Blackburn Rovers at the Riverside Stadium, which have earned him a misconduct charge from the Football Association earlier today.

In a surprise move The Teessiders announced Hignett had left his position as assistant manager with immediate effect, and the Boro head coach has given an explanation.

“We had our differences on decisions and different points of view,” Karanka said. “We all want the best for the club and we talked and agreed that this is the best thing for the club.

“I want to say thank you to him because he knows he is more than an assistant. He is my friend and the first assistant I chose. He has been very important for me in the past eight months and I have him for the rest of my life. He is a legend at this club and I have to wish him the best.

“It was a difficult decision but this is football. We have to try our best for the club and this is the next step. I want to see this club in the highest position and I know Higgy will get other jobs and he deserves the best.”

Karanka has until 6pm on Friday to appeal the FA’s charge after he was sent to the stands by referee Mark Clattenburg after confronting the fourth official.

The Spaniard is likely to receive a touchline ban for his actions, but he was eager stress he did not push the fourth official.

He said: “It has been a difficult few days. It was my first sending off as a coach.

“I want to apologise because I know I made a mistake. I knew one second later that I had, but imagine if you saw what I saw what my feelings were. I lost control and I want to apologise.

“Our crowd don’t deserve my conduct and after the game one member of my staff apologised to the fourth official and the referee and I would like to move on as soon as possible.

“I don’t know what the steps are here in England, but I am ready to explain my actions. I have read that I pushed the fourth official but that is not true. I had an argument with him and I am happy to speak to someone to explain my behaviour.”