Aitor Karanka has extended his Middlesbrough stay by signing a new four-year contract.

The Spaniard guided Boro to the Championship playoff final last season in his first full campaign in charge at the Riverside.

Smoggies chairman Steve Gibson has now confirmed that Karanka has agreed to commit his future to the club, while suggesting that tying the 41-year-old down is the "most important signing" of the summer.

"This is massive statement of the commitment Aitor has to this club," Gibson is quoted as saying by Gazette Live. "For me this is probably the most important signing we will make all summer.

"We know that there has been interest in Aitor over the past year or so from clubs both here and abroad and rightly so because he is a very, very good manager.

"When that speculation has arisen he has always been quick to say that he is happy here and working in the best place. Signing this new four deal underlines that quite clearly. It gives us a lot of stability going into the new season and the coming years."

Boro get their Championship campaign underway on Sunday afternoon with a trip to take on Preston North End at Deepdale.