UNITED NATIONS -UN Secretary-General Ban Ki-Moon said on Tuesday that the use of chemical weapons "under any circumstances" in Syria— whether it be an attack perpetrated by the regime of Bashar Assad or by his opposition— would constitute an "outrageous crime."But Ban's office told the Post that it has no definitive confirmation that such weapons were used this week, amid allegations from both parties in the Syrian conflict that the other had used deadly chemicals in an attack that killed up to 31 people."The Secretary-General has repeatedly made clear that any use of chemical weapons would be a grave violation of international humanitarian law and would be unacceptable," his spokesman said.Few governments have been able or willing to formally assert such confirmation in the wake of the attack. The United Kingdom said it had yet to "fully verify" the claims, and the White House avoided comment as it prepared for President Barack Obama's trip to the region.But the chairmen of both US congressional intelligence committees strongly hinted they had seen evidence that would challenge the president to act. Obama has said that the use of chemical weapons constitutes a "red line" that would prompt direct American intervention in the Syrian conflict.Israeli government sources told the Post they had determined that chemical weapons were indeed used in Syria on Tuesday, when victims were filmed rushing to hospitals complaining of the smell of chlorine.Speaking to Army Radio, newly appointed intelligence and strategic affairs minister Yuval Steinitz said it was "apparently clear that chemical weapons were used," a statement reconfirmed by another senior Israeli defense official to the Associated Press.In a conflict that has taken over 70,000 Syrian lives, only one claim of chemical weapons use has arisen thus far in a country that has the largest stockpile in the region. The incident, in December 2012, went unconfirmed.Thus, the March 19 incident marks the first time in the conflict that the Syrian government acknowledged the use of such weapons. Accusing the opposition of perpetrating the attack, the Assad regime gave no explanation as to how rebel forces would have come into possession of chemical weapons, a missile capable of delivering such weapons, or a launch capacity for such a missile.Syria is one of six countries that has not signed the Chemical Weapons Convention, which prohibits the production, stockpiling and use of such toxins— either lethal or otherwise. Israel has signed, but has not verified, the treaty.