Manchester United are planning to make a move in signing Arsenal captain Thomas Vermaelen this summer, according to the Guardian.

The 28-year-old defender has long been linked with a move away from the Emirates as he has only one year left on his contract at the north London club. The Belgium international's future at Arsenal remains uncertain as he has refused to sign a new deal.

New United manager Louis van Gaal is an admirer and is in the market to sign a central defender. The Dutchman has fielded a three-man defence, along with two full-backs for all the pre-season matches.

Van Gaal believes Vermaelen could fit into the left-side centre back in a 3-5-2 formation. The Red Devils lost Nemanja Vidic and Rio Ferdinand this summer and the former Barcelona and Bayern Munich manager has already admitted his side needs to sign central defenders.

The former Ajax defender was Van Gaal's first summer target at Old Trafford since he agreed to join the Premier League club. Although United have already signed Ander Herrera and Luke Shaw, the two new arrivals were identified by their former manager, David Moyes.

Arsenal are willing to cash-in on the player in the ongoing transfer window. The Gunners value Vermaelen around £12m and United could meet Arsene Wenger side's asking price for the Belgian's signature.

The Gunners boss has already given the green light for Vermaelen's sale after admitting Arsenal's captain could leave the club.

"At the moment, Thomas Vermaelen is here. He is injured at the moment for a short-term injury. It [a transfer] could happen, yes. It's a possibility that he goes. If he goes, we have to replace him because he's an important player in our squad," Wenger told Arsenal's official website.

"No, I expect him to stay but he, of course, did not play enough games last year. For me he's a very important player but I couldn't guarantee him the games he wanted last year."

Meanwhile, United could face competition from Barcelona in landing the centre-back. The same report claims Barcelona are also interested in Vermaelen and Arsenal would be ready to sell their player to a club from another league.

Should Vermaelen join Barcelona, Van Gaal and United need to shift their attention elsewhere in making signings.