the offer was made over night, and has prompted Harry Redknapp to increase his original offer of £5m to £16m.
Despite the latest interest from Italy, Defoe has made no secret of the fact that he always wanted to play under Harry Redknapp, and this was the main stimulus for him signing with Portsmouth in the first place.
"If Portsmouth can agree an acceptable deal with Tottenham I would like the opportunity to talk to them," he said.
"I've enjoyed my time immensely here, but I can't deny that Harry Redknapp's departure as manager hit me hard, particularly because he was the primary reason why I joined Portsmouth in the first place and said so at the time."
The 26-year-old was quick to deny that his desire to leave had anything to do with the appointment of Tony Adams, insisting that his only priority was to return to having Redknapp as his manager.
"It has absolutely nothing to do with it," he said. "I have a great deal of respect for Tony Adams and what he's trying to achieve. We have a very good working relationship.
"But I left Tottenham to join Portsmouth with the intention of working with Harry for a considerable time to come. So it was obviously a big blow when he left and particularly when he went back to my former club.
"I could have gone to other clubs when I left Tottenham but I wanted to work with Harry.
"I enjoy being around him because he brings the best out of me and that is all you can ask for from a manager."
However, while Defoe has become a transfer target, not only for Tottenham and Juventus but also Manchester City, Portsmouth have insisted that they will accept nothing less than their own valuation.
Club chairman Peter Storrie said: "While we accept that Jermain wants to leave, we are under no financial pressure to sell him. And unless someone comes up with a price that we feel reflects his status in the game he is going absolutely nowhere.
"He is an exceptional player and we don't particularly want to lose him.
"But I'll make it quite clear that no one is going to make us sell him."