Puyol will leave Barcelona at the end of the season.Reuters

Barcelona are planning to sign two centre-backs in the summer and according to reports in Spain Liverpool defender Daniel Agger, Chelsea star David Luiz, Tottenham's Jan Vertonghen and Arsenal's Thomas Vermaelen are all on the shortlist.

After legend Carles Puyol recently announced that he will leave the Nou Camp at the end of the season, Barcelona are desperately looking to bolster the back-line.

It is expected that they will sign one centre-back but according to Catalan-based newspaper Sport they in fact are ready to sign two central defenders, even though Javier Mascherano remains in their ranks.

Sport claims that Barcelona are looking for a proven first-choice defender to partner Gerard Pique and a young, low-cost defender to cover the starting duo alongside youngster Marc Bartra, who recently committed his future to the Catalans by signing a new deal.

According to Sport Agger, David Luiz, Vermalen and Vertonghen all have the profile to be Pique's partner next season, alongside Paris Saint Germain duo Thiago Silva and Marquinos and Sevilla's Fazio.

They are also considering FC Porto's Eliaquim Mangala, Real Sociedad's Iñigo Martínez, River Plate's Balanta, Villarreal's Mateo Musacchio and Dinamo Kiev's Aleksandar Dragovic, according to sources close to the club.

Sport reports that Barcelona manager Gerardo Martino has €100m to spend in the summer, with at least half of that available for two centre-backs.

Luiz, Agger and Verntonghen have already been linked with Barcelona in recent times.

With John Terry and Gary Cahill forging Jose Mourinho's preferred starting duo at the back, Luiz has started just 13 Premier League games this season and he may opt to move away in the summer.

Agger has endured a similar situation, with injury restricting him to 12 domestic league games as a starter.

Meanwhile Vertonghen is a pivotal player for Tottenham, but he recently admitted that he may leave White Hart Lane at the end of the season should Spurs fail to secure Champions League football.