According to a statement, the 22-year-old will join the Barclays Premier League outfit on July 1.

Mouyokolo is a highly-regarded prospect in France but Boulogne, who are pushing for promotion to Ligue 1, do not want to lose him before the end of the campaign.

The statement on the club's website, www.usbco.asso.fr, read: "The president and the board of the club have taken the decision to accept Hull City's offer for Steven Mouyokolo.

"The transfer will be effective from July 1, 2009."

Hull are yet to comment.