Liverpool have been admirers of the centre-half for well over a year and will be looking to add to the signing of French striker Djibril Cisse from Auxerre at the end of the season.
Houllier's side lost 2-0 at Paul Sturrock's Southampton today putting a further dent to their Champions League aspirations for next season.
No fee has been mentioned although Chairman Nigel Doughty will looking for at least £4m including a sell-on clause before even considering an offer.
Meanwhile, Michael Stewart, on loan from Manchester United until the end of the season, is the subject of interest from Joe Royle at Ipswich Town.
The 23-year-old has made 13 appearances for The Reds this season but has failed to make an impression on new Forest boss Joe Kinnear.
Royle's side are looking to secure a play-off place this season but will turn to Stewart if they fail to win promotion to the Premiership come May.