Mamadou Sakho
Liverpool are reportedly keeping tabs on the unsettled Mamadou Sakho. (Reuters)

Liverpool are keeping a close eye on Paris Saint Germain's Mamadou Sakho as the centre half continues to stall on an offer of a contract extension.

Brendan Rodgers has wasted little time in adding to his squad this summer having already brought Kolo Toure, Luis Alberto, Iago Aspas and Simon Mignolet to the club.

While the Reds grow increasingly stocked in attacking positions, Liverpool's scant options in defence will be a cause of concern for Rodgers. They are yet to replace Jamie Carragher who retired at the end of last season while uncertainty surrounding the futures of Martin Skrtel and Sebastien Coates persists.

Le Sport 10 report that the Reds are keeping tabs on powerful centre half Sakho who is contemplating his future at the Parisian giants. Despite having been a fixture in the PSG defence since his teens, the 23-year-old was unable to command the first team place he has become accustomed to last season.

Sakho frequently found himself rotated with former Chelsea centre half Alex under Carlo Ancelotti last season with Thiago Silva now holding the role as the club's leading defensive presence.

After Laurent Blanc was named as Ancelotti's successor at Parc de Princes earlier this week, the club may be set to proceed with their summer transfer business having seen Ligue 1 rivals Monaco already spend over £100m improving their squad, something that could put Sakho's role in the first XI in further doubt.

PSG are eager to retain the France international who made his debut for the club at the age of 17 and have offered him a two year contract extension which will keep him at the club until 2016, in addition to a pay rise.

But with next summer's World Cup providing next season with greater incentive to impress, Sakho is aware of the fact that he must be playing first team football every week in order to boost his chances of being called up to Didier Deschamps' squad.

As Sakho ponders his future, Liverpool are likely to address their defensive concerns in the coming weeks. Although the arrival of former Manchester City defender Kolo Toure will have come as a boost, Rodgers will be keen to secure the services of another authoritative presence in his defence following Carragher's retirement.

Liverpool remain linked with Sporting Lisbon's Tiago Ilori and Swansea's Ashley Williams, and Rodgers may have to add more than one name to his defensive options before the transfer window closes.

Slovakian international Skrtel remains linked with a reunion with Rafa Benitez at Napoli after falling drastically out of favour at Anfield last season, while Uruguayan international Coates has yet to impress his manager.