French Foreign Minister Laurent Fabius said on Thursday that UN inspectors who investigated an August 21 chemical weapons attack in Syria would "probably" publish their report on Monday.
Diplomats have said the report is unlikely to pin blame on either Syrian President Bashar Assad or rebel forces in the country, but that it would contain enough detail to suggest which party was responsible.
Foreign Policy quoted US-based diplomats as saying that the UN report will not directly accuse Assad of using chemical weapons against his own people, but it will provide a strong circumstantial case that "points strongly in the direction of Syrian government culpability."
"I know they have gotten very rich samples -- biomedical and environmental -- and they have interviewed victims, doctors and nurses," Foreign Policy quoted a Western official as saying. "It seems they are very happy with the wealth of evidence they got."
Inspections of ammunition and spent rocket casings, as well as laboratory tests of blood, urine and soil suggest that the Assad regime was behind the attack that killed more than 1,400 people, according to Foreign Policy's UN sources.
Depending on its wording, the report could become a bargaining chip in talks between Moscow and the West about placing the weapons under international control.
US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov are due to meet in Geneva on Thursday to try to agree on a strategy to eliminate the chemical arsenal.
Diplomatic sources said earlier that the UN report may come out Monday, as early as this weekend, or later next week.