"The evidence collected establishes reasonable grounds to believe that widespread and systematic attacks against the civilian population have been and continue to be committed in Libya, including murder and persecution as crimes against humanity," Luis Moreno-Ocampo said today.
On Feb 26, the Council slapped sanctions on the Libyan regime including an arms embargo, an asset freeze and travel ban on Muammar Gaddafi and his loyalists, and a referral to the Hague-based International Criminal Court.
A report, released by the prosecutor's office ahead of the Council briefing, said that "the shooting at peaceful protesters was systematic" and "persecution appears to be also systematic and implemented in different cities".
The chief prosecutor said that he will seek three arrest warrants in Libya for crimes against humanity.
"War crimes are apparently committed as a matter of policy," the report said.
The report said that there is "credible information" on the shooting of 500 to 700 civilians in February alone.
"It is difficult to estimate the numbers because dead bodies were removed from streets and hospitals," the prosecutor told the Council.
He said doctors were not allowed to document the number of dead and injured admitted to hospitals after the violent clashes began.
Following the briefing, Hardeep Singh Puri, India's envoy to the UN, urged the prosecutor to carry out an impartial investigation free of non-judicial considerations.
"Political considerations should not exonerate anybody from prosecution for the crimes committed," he said.
Mark Lyall Grant, the UK ambassador to the UN, said that instead of entering into a ceasefire the forces of ColGaddafi were continuing attacks and "excessive use of force".
"Given these indications of dreadful criminal acts, we as the international community must continue to support you in thoroughly investigating these allegations and holding those responsible to account," he said.
Susan Rice, US envoy to the UN, said that the ICC arrest warrants were a warning to those who continued to align themselves with Gaddafi.
"The spectre of ICC prosecution is serious and imminent and should again warn those around Gaddafi about the perils of continuing to tie their fate to his," Rice told the Council. India and the US are not members of the ICC.