Former Arsenal star Ray Parlour believes there is little the club can do to stop Thomas Vermaelen from joining Manchester United this summer.

The Daily Telegraph reported on Monday the Belgian international has agreed in principle to become Louis van Gaal's first signing at Old Trafford.

Although Vermaelen's agent has since indicated the defender has not agreed to leave the Gunners, Parlour believes that his status as third choice defender behind Per Mertesacker and Laurent Koscielny means it will be difficult to stop the club captain from forcing a move that would see him reunited with Robin van Persie at United.

"Thomas Vermaelen wants to play football, it's as simple as that. Last year he couldn't get into the Arsenal side, Mertesacker and Koscielny were fantastic at the back at centre half and Kieran Gibbs has improved so much that he couldn't play him (Vermaelen) at left back," Ray Parlour told the Alan Brazil Sports Breakfast show on talkSPORT.

"So when you get to a situation where players want to move sometimes the player will have more sway than the club itself. If he wants to play football and suddenly an offer comes in from a club like Manchester United sometimes it's hard for the club to say 'no you can't go there, we want to send you to Italy or Spain.'"

Arsenal will already see Bacary Sagna leave north London this summer to link up with former teammates Gael Clichy and Samir Nasri at Manchester City. Given his struggles to find first team football, Parlour believes Vermaelen's particular situation in north London means he is likely to part ways with the club also.

"It was a weird one at Arsenal last season, he (Vermaelen) was doing the captain's notes (in the match programme) before every game and he wasn't even playing and I can't see him getting in the team next season. If Koscielny and Mertesacker start the season and stay fit, they will play, it is as simple as that."

Vermaelen, a £10m arrival from Ajax in 2009, has just one more year on his current Arsenal contract.