Mike Tyson confirmed he will retire from boxing after a humiliating defeat by Irishman Kevin McBride in Washington DC.

Tyson retired on his stool at the end of the sixth round at the MCI Center after a desperate performance against the Clones 32-year-old.

"I'm not going to fight again," Tyson said after the fight, televised in the United Kingdom by Setanta Sports.

The 38-year-old Tyson, who lost his last fight against Briton Danny Williams in July last year, had been docked points in the sixth round for what appeared to be an intentional headbutt as the fight slipped from his grasp.

The first round started slowly with Tyson cautious against the towering Ulsterman, who was similarly tentative.

As McBride tried to use his reach advantage with the jab, Tyson found a way through on a handful of occasions with two rights to the body proving most successful.

Widespread predictions of a second-round stoppage for Tyson proved incorrect with the Clones fighter holding his own, arguably winning both of the opening rounds as a low-blow warning for the American proved the most interesting exchange of the second.

A left hook snapped McBride's head back mid-way through the third as the New Yorker found his range to win the round.

He stepped up a gear in the fourth, 6ft 6ins McBride shrugging off a number of power shots as Tyson threw single punches to the head and body, claiming the round despite a suspect clash of heads and two more punches below the waist.

The bout swung back towards the lumbering Irishman's favour, however, when Tyson, visibly tired in the fifth, was forced to take a number of solid shots.

The increasingly-desperate Tyson was docked two points for another headbutt in the sixth round which split McBride's left eyebrow open. At the end of the round Tyson was pushed onto the canvas and, as the bell went, appeared to struggle to his feet.

And when trainer Jeff Fenech signalled to referee Joe Cortez Tyson had had enough with the fight slipping from his grasp, McBride's corner leapt to their feet in celebration.

The former world champion confirmed he does not want to fight again because he does not have the "fighting guts" to continue.

"I could have continued but I thought I was getting beat on," said Tyson.

"I don't have it anymore. I've got the ability to stay in shape but I don't have the fighting guts anymore. I realised that early in the fight.

"I'm sorry I let everybody down, I just don't have it in my heart anymore."

McBride, though, said: "I told Mike it was going to be fast and it was. I took the fight to him a bit too much.

"He's a warrior and I respect him and I am a warrior. I came with all the heart from Ireland."