Manchester United are losing their grip in their efforts to sign Arsenal skipper Thomas Vermaelen.

The Belgium international has been a transfer target for the Old Trafford club as their new manager Louis van Gaal has set his sights on the central defender to bolster his side’s back four.

United allowed their long serving central defenders Nemanja Vidic and Rio Ferdinand leave the club on a free transfer after the end of the last season. The Dutchman has worked with Vermaelen at Ajax and was keen on linking him up with the 28-year-old at Old Trafford.

However, United’s move for the Belgium centre-back has suffered a road block. According to the Spanish newspaper Mundo Deportivo, Barcelona have now joined the race for the defender’s signature.

Vermaelen has one year left on his contract at the Emirates and is already frustrated with the lack of first team opportunities with the North London club. The La Liga giants recently signed Jeremy Mathieu from Valencia as a replacement for their former skipper Carles Puyol.

The Catalan club were also interested in signing Paris Saint-Germain defender Marquinhos. However, the move to sign the Ligue 1 champions’ centre-back has suffered a blow, which has seen Barcelona shift their attention on United summer target.

Meanwhile, the same report indicated that Barcelona were also interested in signing Daley Blind and Borussia Dortmund’s Mats Hummels. However, the World Cup winning defender is believed to be joining United, leaving the Camp Nou outfit to set their sights on Arsenal defender.

A move from the La Liga giants for Vermaelen would be further encouraged after Wenger admitted that he cannot assure the Belgium international will be at Arsenal next season.

“I cannot guarantee he will stay, but should he go I would bring another centre-back in for sure,” Wenger explained.

It is likely that Vermaelen would leave the Gunners in the ongoing transfer window and Wenger would cash in on the player, rather than letting him leave for nothing at the end of the next season.

Should Barcelona sign Vermaelen, it would allow United make a move for Hummels, if Dortmund are willing to let their star player leave Signal Iduna Park this summer.