A senior Israeli official says chemical weapons were used in the attack in Syria that left at least 100 people dead in the eastern suburbs of Damascus.
Yuval Steinitz, the minister for intelligence and strategic affairs, says Israel's assessment is based on "intelligence estimates." He did not elaborate.
Steinitz told Israel Radio on Thursday that the attack the previous day was not the first time such agents were used.
Steinitz appears to be blaming Syrian President Bashar Assad and calls his regime "exceptionally cruel."
Israel has accused Assad of deploying chemical weapons in the past and has repeatedly expressed concern that neighboring Syria's chemical arsenal could fall into the hands of anti-Israel militants.
The UN Security Council has called for an investigation into the latest allegation of chemical weapons use.