SAO PAULO (Reuters) - A decision on Friday by a Brazilian federal judge to freeze the assets and companies of the billionaire Batista family is  legally fragile  because it is based on newspaper reports and not on prior judicial rulings, the lawyers representing the family s investment holding company J&F Investimentos SA said. In a statement, the lawyers said a decision by Federal Judge Ricardo Leite of the 10th District Court of Bras lia demanding the family deposits 1.6 billion reais ($506 million) to compensate state development bank BNDES is unjustified because J&F was to pay a slightly bigger fine as part of a May leniency accord. Earlier in the day, Leite ordered the assets of the Batistas be frozen as part of an investigation. ($1 = 3.1615 reais) 