John's former club claim they have had a bid which matches the other two Championship sides accepted by Blues for the 27-year-old Trinidad and Tobago international.
Steve Bruce signed John from Forest back in February 2002 for a bargain £100,000 and his goals went a long way in helping Blues return to the top flight two-and-a-half-years ago.
Johns future should become a little clearer when he returns from being away on international duty with the Soca Warriors later this week.