Israel Radio said on Monday that Israel has evidence backing Syrian opposition accusations that forces loyal to President Bashar Assad had used non-lethal chemical weapons in Damascus last month.
The report quoted an unidentified senior Israeli defense official as saying there were two attacks on March 27, using a "neutralizing chemical weapon", east of Damascus and at another location.
The report was broadcast shortly after Defense Minister Moshe Yaalon met the Israeli media. There was no immediate comment from government officials.
Last Thursday, opposition activists accused Assad's forces of using poison gas, showing footage of an apparently unconscious man lying on a bed and being treated by medics.
The alleged attack, the activists said, was carried out in Damascus's Jobar neighborhood. Reuters could not independently verify the footage or the claims due to security restrictions on reporting in Syria.
One opposition group, the Syrian Revolutionary Coordinators Union, said that all those affected by the gas were "in a good condition". There has been on-off fighting between rebels and government forces in Jobar this year.
A U.N. inquiry found in December that sarin gas had likely been used in Jobar in August and in several other locations, including in the rebel-held Damascus suburb of Ghouta, where hundreds of people were killed.
The inquiry was only looking at whether chemical weapons were used, not who used them. The Syrian government and the opposition have each accused the other of using chemical weapons, and both have denied it.
The Ghouta attack sparked global outrage and a U.S. threat of military strikes, which was dropped after Assad pledged to destroy his chemical weapons.
But the Syrian government failed to meet a February 5 deadline to move all of its declared chemical substances and precursors, some 1,300 tonnes, out of the country. Israel Radio quoted the defence official as saying the material used on March 27 was not
on the list of chemicals due to be removed.
Syria has since agreed to a new timetable to remove the weapons by late April.
Syria's three-year civil war has killed more than 150,000 people, a third of them civilians, and caused millions to flee.
Reporting by Jeffrey Heller, Editing by Crispian Balmer