Brook, 30, has been linked to facing Khan in a massive UK clash in the spring, although number one contender Spence has been patiently waiting his stipulated turn for the past few months.
Spence even took it on the chin when Brook fought Gennady Golovkin at middleweight in September, but is now seeking the outcome of a purse bid on February 26, by which time the American should know more regarding his title shot.
As WBN revealed last year, Brook could apply to the IBF Board of Directors to give special dispensation to defend his belt against Khan, although no such request has been put forward by the champion.
“The IBF ordered Kell Brook to defend against mandatory challenger Errol Spence. We never received a request for Brook vs. Khan,” IBF Chairman Lindsey Tucker exclusively told World Boxing News.
Tucker went on: “The fact is, Khan is not even in the IBF Ratings. We heard a lot of talk about Brook vs. Khan but we never received anything from either side.”
Talks picked up between Brook and Khan in early January following the festive period and the bout remains the number one target for Matchroom promoter Eddie Hearn to secure for the coming months.
A recent scandal and family problems involving Khan could scupper those discussions over the next few weeks, which could then put Spence in the pole position to battle Brook in the UK.
As things stand, Brook v Khan in any title capacity is not on the table, but if talks are successful, an application to delay the Spence fight will have to be made before any agreement is signed.