Last month, 17-year-old Crellin penned a two-and-a-half-year contract with the League One side, despite not making his first-team debut for the club.
Fleetwood acted after Crellin played a role in England's triumph at the Under-17 World Cup earlier this year, with Manchester United, Arsenal and Everton said to be monitoring the youngster's progress.
However, according to Football Insider, Fleetwood have shown their intent to keep Crellin at Highbury Stadium by turning down an offer from Championship leaders Wolves.
The West Midlands outfit are well stocked for goalkeepers in both the first team and reserve setups, but head coach Nuno Espirito Santo allegedly sees Crellin as one for the future.
Crellin was on the bench as England defeated Spain in the World Cup final, but the player did feature in the 4-0 victory over Iraq during the group stages.