MILAN (Reuters) - Shares in Italy's Bio-on fell 50% and were immediately suspended from trading on Thursday after U.S. hedge fund Quintessential Capital Management raised fresh doubts over the bio-plastics company's accounts. In a statement, its third in the past 24 hours, Bio-on denied accusations of accounting irregularities and fictitious revenues made by Quintessential - a fund which has said it has an economic interest in the price movement of Bio-on's shares. Quintessential, however, said the statement by the company failed to address its criticism, adding it would publish new documents in coming days.