Sanchez posted an Instagram message thanking Arsenal staff, teammates and fans on Monday after completing his highly anticipated move to Manchester United. But he also aimed a dig at pundits who have questioned his commitment in recent weeks.

"There are people (former club players) who have spoken with no knowledge of what happens inside the club and cause damage. I must say I always gave 100 percent, until the last day, when I asked to the Mister [manager] to be in the team, because I wanted to be a contribution."

Arsenal great Thierry Henry raised questions over Arsenal's team unity following their win at Crystal Palace last month, when the Sky Sports pundit highlighted how some players didn't celebrate Sanchez's first goal with the Chilean.

Sanchez didn't specify which former players he was referring to, but he referenced the French striker when discussing his reasons for leaving Arsenal.

"I remember today, a conversation I had with Henry, a historic Arsenal player, who changed club for the same reason and today is my turn," Sanchez wrote.

"Thanks for everything Gunners! All we achieved and the good moments that I gave to the club, I want to dedicate it to the fans, they are the most important. Thanks for every time you sing Alexis Sanchez Baby."