UNITED NATIONS, April 4 (Xinhua) -- UN Secretary-General Antonio Guterres on Tuesday said he is deeply disturbed by reports of alleged use of chemical weapons in an airstrike in Syria's northwestern province of Idlib.
Media reports said about 70 people were killed, 200 others were wounded Tuesday in a gas attack in a rebel-held area in southern Idlib.
"The United Nations is not currently in a position to independently verify these reports," said a statement released by Guterres' spokesperson.
According to the statement, the Fact Finding Mission of Organization for the Prohibition of Chemical Weapons (OPCW) has announced that it has begun gathering information to confirm the use of chemical weapons.
Guterres also noted that the Security Council has determined the use of chemical weapons anywhere constitutes a serious violation of international law.
Earlier, the Syrian Observatory for Human Rights said warplanes launched intensive airstrikes on the rebel-held town of Khan Sheikhoun in Idlib, killing 58 people, mostly civilians.
The Syrian opposition accused the Syrian Air Force of being behind the attack.
Without providing proof, the U.S. government condemned the gas attack as "heinous actions" by the Syrian government.
The Syrian army categorically denied launching such a toxic attack, the Syrian state news agency SANA reported on Tuesday.
The Syrian army said the accusations against it were completely baseless as it had not used, nor would use such weapons in the future. It held "terrorist groups" responsible for using chemical weapons.
The United Nations special envoy to Syria Staffan de Mistura said the attack was believed to be chemical and was launched by air, noting there ought to be a "clear recognition of responsibility and accountability."