By Edward Chaykovsky

IBF welterweight champion Kell Brook (36-1, 25 KOs) is still undecided on his next move.

In his last fight, which took place in September 2016 against Gennady Golovkin, Brook moved up by two weight divisions in a failed attempt to capture the unified middleweight crown.

Brook's team was trying very hard to finalize a May blockbuster with Amir Khan - but their negotiations fell apart on Monday - after Khan demanded a 70-30 monetary split in his favor.

With Khan out of the mix, for now, Brook has an order from the sanctioning body to make a mandatory defense against undefeated Errol Spence (21-0, 18 KOs).

Before he makes a decision on fighting Spence, Brook plans to start training to determine if he's still capable of making the welterweight limit of 147.

If his body begins to struggle, then Brook will vacate the IBF title and move up to the junior middleweight division.

"It's so, so frustrating," said Brook to Sky Sports. "Everybody wants this fight so badly and I desperately want to give them this fight. We've come to a dead end at the minute.

"I'm going to get back in the gym now, I'm going to start dieting. I'm going to be listening to my body and see if I can get down to a certain weight, so many weeks before the fight when we're making welterweight. I'm just going to see if we move to 154, or if we fight Spence. I'll probably be able to let you know in the next two or three weeks where I think we will be going."

Brook's promoter, Eddie Hearn of Matchroom Sport, would rather have his fighter move up to 154.

"I have to say that 147-pounds for Kell Brook is not a good move. He's struggled to make that weight for a long time. He made 160 [for Golovkin] and made it very well but it was a little too much weight. But why deplete yourself when you can be such a better fighter at 154-pounds," Hearn said.