Portsmouth insist Laurent Robert has signed for them on a permanent basis and not, according to reports, on loan.
Robert spent four years at Newcastle
Confusion arose about the move after Magpies chairman Freddy Shepherd said Robert would not be allowed to play against Newcastle next season.
Such restrictions do not occur in permanent deals but Pompey chief executive Peter Storrie said: "He is with us for three years."
The 30-year-old winger signed for Portsmouth for an undisclosed fee.
Storrie added: "The only get-out clause to this would be if we are relegated but this is merely precautionary and a sensible move.
"We would not be signing players with the ability of Laurent if we thought we would be playing Championship football in a year's time.
"And Laurent would not be signing for us if he didn't believe the same."
Robert had a fractious relationship with Newcastle boss Graeme Souness following Sir Bobby Robson's departure.