DUBAI, March 6 (Reuters) - Iran's supreme leader said on Monday that the poisoning schoolgirls is an "unforgivable" crime that should be punished by death if deliberate, state TV reported, amid public anger over a wave of suspected attacks in schools. The White House called for an independent investigation to determine if the poisonings were related to protests, which would make it well within the mandate of the United Nations fact-finding mission on Iran. See here for a complete list of exchanges and delays