Speaking to the Ipswich Evening Star former West Ham boss and current Pompey boss Redknapp said: "Marcus is a player with bags and bags of ability. He has strength, pace and is good in the air.
"But the question mark over him is why he has been to so many clubs. That's the gamble. It's about him putting it all together on a regular basis. But I wouldn't pay a fee for him - not a penny."
Bent was earlier this morning linked with a move to West Bromwich Albion and Scottish giants Celtic and Rangers are also said to be monitoring the situation closely.