Sporting director Robert Fernandez and Barca scout Urbano Ortega travelled to London to see two key fixtures.
On Monday, Chelsea took on rivals West Ham as Antonio Conte’s side prevailed 2-1 winners to extend their lead at the top of the Premier League table.
The performances of Eden Hazard and N’Golo Kante were particularly impressive at the London Stadium.
Chelsea's Cesar Azpilicueta and Marcos Alonso celebrated victory at West Ham with Barcelona watching
However, according to Spanish newspaper Marca, Barca were at West Ham’s new home to seek out defensive reinforcements.
It is said Fernandez and Ortega paid attention to Cesar Azpilicueta and Marcos Alonso, with the La Liga giants keen to strengthen in the full-back area.
Bolstering midfield options is also on Barca’s agenda, and Nemanja Matic’s 20 minutes from the bench was also taken into account.
Marcos Alonso claimed this week he rejected Barcelona last summer to go to Chelsea
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Mon, March 6, 2017
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Hector Bellerin was apparently the main focus, although little was made of the game
The following day, the Barca duo went up to north London to watch Arsenal’s Champions League clash with Bayern Munich.
Despite the 5-1 first leg deficit, the Gunners held slim hopes of mounting a comeback and had motivation to perform.
And long-term Barca target Hector Bellerin was apparently the main focus, although little was made of the game as Arsenal capitulated in the second half with just 10 men.
Right-back Hector Bellerin endured a difficult night in Arsenal's defence against Bayern Munich
Matic, Azpilicueta, Alonso and Bellerin are all targets ahead of the summer transfer window, but the La Liga giants potentially face one problem.
The Catalan club could swoop for one of the London talents on their radar, but meeting demands or convincing players to take a pay cut may prove difficult.