Wenger believes Campbell could play his way back into the England squad for the World Cup in South Africa in the summer.
Wenger said: "It (England) is not the immediate target but you should not rule anything out.
"That is not my worry and my job but if you were in his position what would you want to do? You would want to give your best and you never know. It is unlikely maybe, but if you are in his shoes you would say 'Let's give as much as I can' and you never know."
Wenger said: "I have seen him in training and he is very sharp. His attitude is good, his talent is good. But it is the game which decides."
When asked whether he regretted allowing Campbell to leave in 2006, Wenger said: "Life is life. He wanted to go abroad. I did not make him leave. He wanted to go. We live in a world where everybody is free to do what he wants with his life.
"It gives us the opportunity to have one more centre-back. Sol will give us experience, good advice and physically he has worked very hard.
"It is an opportunity for him to relaunch his career and for us it is a good help for the rest of the season. He is dedicated, motivated and looks happy to be back."