The U.N. chief is expected to present a report on the use of chemical weapons in Syria to the Security Council on Monday morning.

Secretary-General Ban Ki-moon says he believes there will be ``an overwhelming report'' from U.N. inspectors that chemical weapons were used in an attack in Syria on Aug. 21, but he isn't saying who was responsible.

The U.N. inspectors have a mandate to determine whether chemical weapons were used _ and if so, which agent _ not to establish who was responsible. But two U.N. diplomats said the report could point to the perpetrators, saying that the inspectors collected many samples from the attack and also interviewed doctors and witnesses.

The chief chemical weapons inspector has said he will deliver his report on the attack to Ban this weekend. Two U.N. diplomats said late Friday that Ban would was expected to brief the council about it on Monday morning.

The diplomats spoke on condition of anonymity because the time was not yet final.