Volkswagen Polo wheels squeeling while cornering

I have recently noticed that when I go around islands my wheels are making a squeeling noise. At first I thought I was simply cornering too fast, but having slowed down dramatically when cornering, I have found that it is still there. I have checked the tyres and they seem fine with plenty of tread.
A friend suggested that it could be the bearings. Is this the most likely problem and if so, could it be hazardous and how much would it cost to repair?