The chief prosecutor for the International Criminal Court says he intends to indict three Libyan officials for crimes against humanity, within the next few weeks.
Luis Moreno-Ocampo did not give any names but told the UN Security Council that crimes were continuing.
The forces of Libyan leader Muammar Gaddafi have been fighting an anti-government uprising for two months.
He said evidence has been found of systematic shooting at peaceful protestors, and the persecution and torture of those suspected of being opponents of the government.
He said the instructions came right from the top of the Libyan leadership.
Mr Ocampo said the precise number of victims of the conflict is impossible to establish.
He noted that between 500 and 700 people were estimated to have been killed in Libya in February alone.