Thomas Vermaelen
Thomas VermaelenReuters

Arsenal have rejected a bid from Manchester United for Thomas Vermaelen, according to reports.

Vermaelen -- who joined the Gunners from Ajax in 2009 for £10 million -- has not been a regular in Arsene Wenger's side for nearly 18 months after being sidelined by Per Mertesackaer and Laurent Koscielny.

The Telegraph reported on Monday the Belgian international had agreed in principle to become Louis van Gaal's first signing at Old Trafford where the Dutchman is expected to make sweeping changes to a squad that recorded the club's worst ever league finish in the Premier League era.

But, according to the Mirror, Wenger is reluctant to lose the defender to a direct rival after being strongly criticised for accepting the Red Devils' offer for Robin van Persie two years ago. Also he is unwilling to let him leave the club without having a replacement lined up.

Vermaelen -- who is currently on World Cup duty with Belgium -- recently insisted he had not yet made a decision on his future. "I know there has been a lot of talk and a lot of rumours but the only thing I can say is that it's not true.

"Everybody understands my situation at Arsenal and that I have one year left. I understand that people are going to talk but I am here in Brazil and I am enjoying my time and I am focused on what I am doing."

The lack of clarity about his future suggested he may join Bacary Sagna in leaving the Emirates this summer, but the skipper refused to be drawn on his talks with the club – now it seems clearer though.

The 28-year-old has just one year remaining on his current contract which means he can leave the Emirates for free next summer – so in order to avoid that, Arsenal are ready to offer the Belgian a new contract this summer.