Charles is understood to have accepted the payment from Bakr bin Laden, head of the family, and his brother Shafiq - both half-brothers of 9/11 mastermind Osama.
The watchdog said it has looked at the information and has decided against intervening following allegations Charles was reportedly given three million euros by a former Qatari prime minister.
BREAKING: Prince Charles will never again handle large cash donations to his charities after he was presented with €3m stuffed into bags from a former Qatari prime minister.
The probe was launched after it was revealed the prince s aides helped to fix a CBE for Saudi billionaire Mahfouz bin Mahfouz, who had offered to donate millions.