Wenger has ruled Walcott out for the remainder of the season after the midfielder hobbled off the Emirates pitch clutching his hamstring in Arsenal's 0-0 draw with Chelsea on Saturday.
Wenger said: "It looks like a serious hamstring. First we assessed the hamstring, he wanted to go on and stay on the pitch, and I think he should have gone off straight away because the second time it was a real hamstring [injury].
"I think now for him it will be tough to come back before the end of the season. It is usually 21 days [minimum]."
"He should be OK to play for England, but I don't think he will be ready to play for us."