Redknapp said: “It’s no secret Derby would like to buy David.
“They have been in and would like to sign him, they would like him very much.
“Billy Davies knows him and if people want to move, you have to let them go.
“It’s up to David really. I’ll have a chat with him and see what his plans are.”
Redknapp also admitted they are looking for a big-name striker but played down reports that Bolton ace Nicolas Anelka could be heading to Fratton Park.
He added: “We are looking for a striker. If I do bring one in it would be a good one, that’s for sure, it won’t be just anyone.
“I doubt it would be Anelka. I like Anelka but I doubt that very much.
“You need someone in your side who can get you 15 to 20 goals a season, although there’s only a certain amount of people capable of doing that.
“I might have to sacrifice one or two players who people think are good because I want to improve the team.
“It’s not a case of if it’s David or someone else. If I have to raise some money to buy a top player, it’s who you get an offer for.”
