Greek police on Friday have clashed with protesters in Athens and fired flash bombs only two days before Sunday's bailout referendum.The clashes have erupted in Athens' main square when a few dozen people rallied in support of a "no" vote in Sunday's referendum on whether the country will accept proposed reforms in exchange for bailout loans.According to the witnesses, after firing tear gas at the crowd, the riot police were chased away by the protesters and the situation went back to normal.