"Hey murderer Assad, how are you going to escape from their curse?" Erdogan said at a rally in the western city of Bursa, referring to the victims.
At least 72 people, among them 20 children, were killed yesterday's attack in rebel-held Khan Sheikhun, and dozens more were left gasping for air, convulsing and foaming at the mouth, doctors said.
Erdogan, in his first public reaction to the incident, said that more than 100 people, including children, "became martyrs due to chemical weapons".
The UN Security Council was meeting today to discuss a draft resolution presented by Britain, France and the United States that urges a swift investigation into the attack.
More From This Section
Erdogan, a vocal critic of Assad, also denounced the world's "silence" on the killings.
"Hey, the world that remains silent, the United Nations that remains silent. How will you be brought to account for this?" Erdogan said.
Russia, Assad's main ally, has said a Syrian air strike had hit a "terrorist warehouse". Erdogan made no reference to the Russian claim.
The wounded were brought from Idlib for treatment in the Reyhanli district of Turkey's southern Hatay Province.
"We are doing our best but that's not enough," Erdogan said. "They are our kids, our brothers. I am sad as a father."
Hours after the attack, Erdogan told his Russian counterpart Vladimir Putin by phone that "this kind of inhuman attack was unacceptable".
Turkey also informed Russia and Iran that the attack was a violation of a fragile ceasefire brokered between Ankara and Moscow, Turkish foreign ministry spokesman Huseyin Muftuoglu said.
Shortly after Tuesday's attack in Idlib, Turkey contacted the Russian and Iranian embassies in Ankara, reminding the "two guarantor countries" of their responsibility to prevent repetition of similar violations, the spokesman added.
Years of diplomatic efforts have failed to end the Syrian conflict, which has killed more than 320,000 people and displaced millions since it started in March 2011 with protests against Assad's regime.