Khan dominated the encounter against his Doncaster opponent

The 20-year-old from Bolton made a solid start against his experienced Doncaster opponent and was well in control in the opening two rounds.

Once Khan got a chance in the third round he landed a left-hand body shot which caught Bull.

Khan kept up the pressure and soon wrapped up his 12th pro fight victory.

After his last victory against Mohammed Medjadi, which he completed in just 55 seconds, Khan was once again in impressive form.

Bull, who boasted a 24-4-1 record, had come out of a short-lived retirement to take the fight.

The 29-year-old could not cope with the hand speed of Khan and spent virtually all of the first round on the back foot.

Two left hands right on the bell hurt Bull, who was also winded by a crunching right to his body early in the second as he pulled up a tight guard.

It was a good fight and I take away some experience Amir Khan

Khan had more success early in the third when he backed Bull against the ropes and jolted his head back with a right hand.

It proved to be the beginning of the end for Bull and he was subjected to a flurry which dumped him to the canvas.

Bull beat the count, but referee Marcus McDonnell waved the contest off, leaving Khan celebrating another success.

"It was a good fight and I take away some experience," he said afterwards.

"I've been in the ring for three rounds. I put my hands higher and I didn't rush.

"He was an experienced lad and I had to move and pick my shots. I had to get him slowly. I couldn't rush him."

Khan insisted he is already the "best lightweight in Britain" and predicted that "very soon" he will be the best lightweight in the world.

But promoter Frank Warren, clearly determined not to rush things, said: "He's getting there but he's got a while before he gets to the world.