National youth coach Ross Mathie said: "Cameron's father is Scottish, which is why he's eligible for us. He played for England in an Under-17 qualifying match against Estonia last October but Sir Alex Ferguson is obviously trying to get him to come to us.
"I spoke to George Burley earlier this week and he said Sir Alex had mentioned Cameron to him but Alex had also told Alex McLeish about the lad when he was here. Because of that he was already on our radar. In fact, Archie Gemmill has been to watch him in action for United's youth side.
"We named him in the squad for the trip to Malta last month but United had a youth game against Carlisle and Brian McClair had to pull him out.
"We're keen to have him along so we can have a look at him. We really just want to know his thoughts. If he's dead set on playing for England that's fine, but if he hasn't decided we want to declare our interest."
Stewart could get the call before the youth team's European Championship ties in Northern Ireland next month.