By Ben Dirs in Cardiff

Khan was too strong for Steffy Bull

Amir Khan rounded on his British rivals after securing his 12th professional victory in Cardiff on Saturday.

Khan stopped Steffy Bull before stating he wanted to challenge British champion Jonathan Thaxton later this year.

"There are a few fighters I'd love to fight just to shut their mouths. They're scared," said 20-year-old Khan.

"Thaxton is made for my style, he's a come-forward fighter and I've got the hand speed to pick him off and stay away from his bombs."

Norwich's Thaxton, 32, won the Lonsdale belt from Lee Meager last December and has defended it once, against Stoke's Scott Lawton last month.

Bolton's Khan, an Olympic silver medallist in 2004, added: "If you watched him against Ricky Hatton, Hatton gave him a boxing lesson, and I'd do the same.

"Then there's Commonwealth super featherweight champion Kevin Mitchell, although he's gone a bit quiet lately.

He has incredible hand speed, power, confidence, everything. The kid is going to be a superstar Sugar Ray Leonard on Amir Khan

"And former British lightweight champion Graham Earl, although he's been quiet since the last fight he had."

Earl's last bout was a brutal WBO interim title defeat to Australia's Michael Katsidis in February.

Manchester's John Murray, the WBC Youth champion and 2006 British boxing writers' young fighter of the year, also challenged Khan last week, but Khan shrugged off the 22-year-old's claims.

"I've sparred with Murray and played around with him and he's not even on my level," said Khan.

"I'm happy for him that he's fighting in America on the undercard of Oscar de la Hoya-Floyd Mayweather on 5 May.

"But I think everyone knows who's better. They're scared and they want a big pay-day. But I'm not scared, I'll fight anyone."

Khan said that his fight against Doncaster boxer Bull was another important lesson, despite it lasting less than three rounds.

"The guy made me think - instead of me just going in there and throwing punches I learnt how to fight someone who is travelling backwards," said Khan.

"I had to change my style and keep on putting pressure on. I wanted him to come forward at one point, but then I thought 'I'm catching him, so I'll keep on doing what I'm doing'."

Promoter Frank Warren confirmed that Khan's next fight would be for a title, but did not say whether it would be for the British crown.

"Amir fought a guy who was very defensive, thought about what he was doing, slowed it down and hit him with good body shots," said Warren.

Maccarinelli defended his title in Cardiff

"Amir will have a title fight in July, but I don't know which. It's very difficult to see how you can hold him back."

Meanwhile, American legend Sugar Ray Leonard, who was in Peter Manfredo's corner for his fight with Joe Calzaghe, said Khan was destined for greatness.

"He has incredible hand speed, power, confidence, everything. As long as he's moved correctly and patiently, the kid is going to be a superstar," said Leonard.

Warren said that Enzo Maccarinelli could be manoeuvred into a unification fight this summer.

Wales' Maccarinelli defended his WBO cruiserweight belt with a first-round stoppage of American Bobby Gunn in Cardiff.

"We'd like to make a fight with France's WBC and WBA champion Jean Marc Mormeck," said Warren.

"Mormeck is supposed to be fighting London's European champion David Haye, but I think it's debatable that Haye will ever make the weight again.

"And then there's Poland's IBF champion Krzystof Wlodarczyk - we'll be making him an offer on Monday for a unification.

"I think Enzo is one of - if not the - hardest punchers in the world. If he catches you, you're gone."