Pompey value Johnson, who only signed a new four-year contract in January, at about £18m and would only allow him to leave if their valuation was reached.
"Glen has obviously had a fantastic season for us and has established himself as one of the best right-backs in the league if not the country at the moment," former West Ham managing director Storrie told Sky Sports News.
"I've known Glen for a long time since his West Ham days so when I re-signed him we talked it over and he asked if one of the big four clubs, who were in the Champions League, came in for him would we stand in his way of a move.
"I said that I couldn't do that, provided the deal is good for Portsmouth and for Glen."
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