UN Secretary General calls evidence of chemical attack in Syria 'indisputable'

United Nations Secretary General Ban Ki-Moon said Monday that results of a report by U.N. inspectors confirming the use of chemical weapons in Syria are “overwhelming and indisputable.”

“This is a grave crime. Those responsible must be brought to justice and soon as possible.“ Ban told reporters at U.N. headquarters in New York. He also emphasized that this is the largest chemical attack in many years.

U.N. inspectors said Monday that there is "clear and convincing evidence" that chemical weapons were used on a relatively large scale in an attack last month in Syria that killed hundreds of people, including civilians. Ban presented their report to a closed meeting of the U.N. Security Council in New York Monday morning.

The findings represent the first official confirmation by scientific experts that chemical weapons were used in Syria's civil war, but the report left the key question of who launched the attack unanswered. The rebels and their U.S. and Western supporters have said the regime of President Bashar Assad was behind the Aug. 21 attack, while the Syrian government and its closest ally, Russia, blame the rebels.

Secretary of State John Kerry briefed U.S. allies on a broad agreement reached over the weekend with Russia to end Syria's chemical weapons program, pressing for broad support for the plan that averted U.S. military strikes.

Kerry met in Paris with his counterparts from France, Britain, Turkey and Saudi Arabia before seeking a U.N. resolution that would detail how the international community can secure and destroy Syria's stockpile and precursor chemicals.

As a sign of possible difficulties ahead, Kerry and Russian Foreign Minister Sergey Lavrov sparred Monday over possible military action if Syria doesn't abandon its chemical weapons.

And in Geneva, the chairman of a U.N. war crimes panel said it is investigating 14 suspected chemical attacks in Syria, dramatically escalating the stakes. Paulo Sergio Pinheiro said the panel had not pinpointed the chemical used or who is responsible.

The inspectors' report said "the environmental, chemical and medical samples we have collected provide clear and convincing evidence that surface-to-surface rockets containing the nerve agent sarin were used ... in the Ghouta area of Damascus" on Aug. 21.

"The conclusion is that chemical weapons have been used in the ongoing conflict between the parties in the Syrian Arab Republic, also against civilians, including children, on a relatively large scale," the inspectors said in their report to Ban.

"This result leaves us with the deepest concern," the inspectors said. The inspectors were mandated to report on whether chemical weapons were used and if so which ones -- not on who was responsible.

The rebels and their Western and Arab supporters blame President Bashar Assad's regime for the attack in the rebel-controlled area of Ghouta. The Assad regime insists that the attack was carried out by rebels. The U.N. report mentions the Ghouta areas of Ein Tarma, Moadamiyeh and Zamalka, all of which were featured in the videos of victims that emerged shortly after the attack.

The report cited a number of facts supporting its conclusion:
-- Rocket fragments were found to contain sarin.
-- Close to the impact sites, in the area were people were affected, "the environment was found to be contaminated by sarin."
-- Blood, urine and hair samples from 34 patients who had signs of "intoxication" by a chemical compound provided "definitive evidence of exposure to sarin by almost all of the survivors assessed."
-- More than 50 interviews with survivors and health care workers "provided ample corroboration of the medical and scientific results."
The inspectors described the rockets used to disperse the sarin as a variant of an M14 artillery rocket, with either an original or an improvised warhead. The report said the origin of the rockets was from the northwest, but gave no specific location and didn't point a finger at the perpetrator.

The inspectors cautioned that the five sites they investigated had been "well traveled by other individuals prior to the arrival of the mission."

Kerry and his French and British counterparts worked on a two-pronged approach to Syria. They called for enforceable U.N. benchmarks for eradicating the chemical weapons program and an international conference bolstering the moderate opposition.

An ambitious agreement reached with the Russians calls for an inventory of Syria's chemical weapons program within one week, with all components of the program out of the country or destroyed by mid-2014.

In London, Syrian Information Minister Omran al-Zoubi said Syria will comply with all Security Council resolutions and will facilitate the mission of the U.N. inspectors in line with the Russian-U.S. agreement. The comments were carried by state-run SANA news agency, which said al-Zoubi made the comments in an interview with Britain-based ITN TV on Sunday.

The Associated Press contributed to this report.