Paul Butler of England on Wednesday announced that he was vacating his bantamweight world title and dropping back to junior bantamweight, the division where he has fought most of his career.

"It's a beautiful belt and it's hard to relinquish it seeing as it's the first world title that I've won, but I knew that it was always going to be the case if I won it I'd have to return it and go back down," Butler said.

The 25-year-old Butler (16-0, 8 KOs) won a split decision against countryman Stuart Hall on June 7 to claim the 118-pound title, but rather than defend it he said his aim is to win a belt in the 115-pound division.

"When the opportunity came to fight Hall for the title I knew that it was a fight that I could win, and I grabbed the chance with both hands," Butler said. "To become a world champion in only my 16th fight was an absolute dream come true. Obviously, there was a big size difference between me and Hall, but I said to everybody that I could overcome him with my speed and work-rate and that proved to be the case, but I'm a natural 115-pounder.

"Now I aim to win a world title at [junior bantamweight] and achieve another dream of becoming a two-weight world champion in reverse. Most of the British greats have gone up through the weights like Duke McKenzie, David Haye, Ricky Hatton, Nigel Benn and Chris Eubank to name a few. But only Bob Fitzsimmons has achieved the feat of dropping down a weight and that will be a big incentive for me."

More than 100 years ago, Fitzsimmons won the heavyweight title and later dropped down in weight and won the light heavyweight title, although that was in an era with one champion per division as opposed to today's era with several belts available in each weight class.

Eventually, Butler said he might return to bantamweight.

"Of course, another return to bantamweight isn't out of the picture in the future," he said. "I'm still only 25 and in the next couple of years I could fill out and mature some more and be more comfortable at that weight, but for now I'm focused on winning and unifying titles at [junior bantamweight]."

To fill the vacancy, the IBF said it will order Randy Caballero, who loomed as Butler's mandatory challenger, to face an opponent to be determined. Caballero (21-0, 13 KOs), 23, of Coachella, California, traveled to Japan and knocked out Kohei Oba in the eighth round on April 4 in the elimination bout to become the mandatory challenger for the belt.