Jewell's opposite number, Steve Cotterill, had submitted a £800,000 offer for the 25-year-old, whose contract expires at the end of the current season.
Pompey midfielder David Norris joined the club from Ipswich in the summer and Jewell believes that he may have played some part in the offer.
"Perhaps Chuck [Norris] has blown in Steve Cotterill's ear," said the Ipswich boss.
"We want Grant to stay here and have offered him a new contract. We want him to sign another deal with us to secure his future.
"He is my captain and I feel he has great deal more to offer the club."
Leadbitter joined the Blues in 2009 from Sunderland for a fee in excess of £2m.