Manchester United have received a massive encouragement in their pursuit of signing Thomas Vermaelen after Arsene Wenger admitted the defender could leave Arsenal.

The 28-year-old saw his first team appearances being limited last season. He was sidelined due to injury, which saw the Gunners' manager field Per Mertesacker and Laurent Koscielny in the heart of the defence and the two were impressive.

Vermaelen has one year left on his contract at the Emirates and has not signed a new deal. The Belgium international has strongly been linked with a move to United as the centre-back looks to reunite with the Red Devils' new boss Louis van Gaal at Old Trafford.

Wenger says he will not be able to provide any assurance that Vermaelen would stay on at Arsenal. However, the Frenchman confirmed the north London club will bring in a replacement if the Belgium decides to end his time at the north London club.

"I cannot guarantee that [he will stay at the club] but should he go, I will bring another centre back in for sure," Wenger told Arsenal's official website.

Should Vermaelen make a switch to Old Trafford, he will be the second player after Robin van Persie to leave Arsenal for United in recent times.

United had a disastrous season under David Moyes last season as they finished seventh in the league table. The Red Devils sacked the former Everton manager 10 months into his six-year contract.

Van Gaal replaced Moyes at Old Trafford and Wenger has backed United's decision in appointing the former Barcelona and Bayern Munich boss as their new manager.

"What is important is our performances. I believe that Manchester United have appointed a great manager who has shown during the World Cup that he's top quality. It will certainly be difficult for us but for other competitors as well. We are all at the same level," the Arsenal manager said.