It's not exactly fair to be spreading rumours about Nokia chargers when you have no idea if it's true or not. A quick Google shows up nothing of substance. I'd be very doubtful about the accuracy of the claim.
I have heard this before, if you search more indepth you will find some info
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Nokia Batterys have also caused fires : [broken link removed]
Apple iPhones also had cause to be concerned : http://www.tomsguide.com/us/apple-iphone-charger-fire-electrocution,news-2622.html