The 29-year-old Portuguese player, Mendes, who won the Champions League with Porto in 2004, played a crucial role in saving Harry Redknapp's side from relegation in 2006 and then in their FA Cup success last season.

But the former Tottenham Hotspur player has now signed a three-year deal with the Scottish side bringing to an end a two-and-a-half year spell on the Southcoast.

Portsmouth have however completed the signing of Jerome Thomas on a season-long loan from Charlton Athletic.

good addition

Redknapp has been a long-term admirer of the winger after trying to sign Thomas during January's transfer window.

Pompey's chief executive Peter Storrie said: "Jerome's a young player that Harry has always liked - a quick, wide player who is a good addition to the squad.

"The idea is that he comes here and proves himself. If he plays to the ability we all know he has then he has a great chance of staying here longer, so it's in his hands."