At least 72 people, among them 20 children, were killed in Tuesday's attack in rebel-held Khan Sheikhun.
"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 in Tuesday'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 over 100 people, including children, "became martyrs due to chemical weapons".
The World Health Organization said there was reason to suspect a chemical attack, with some victims displaying symptoms suggesting exposure to "a category of chemicals that includes nerve agents."
The UN Security Council was meeting Wednesday to discuss a draft resolution presented by Britain, France and the United States that urges a swift investigation into the attack.
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.
Turkey said Wednesday that about 30 people were being treated in Turkish hospitals after the attack, adding that it had evidence the strike was caused by chemical weapons.
The wounded were brought from Idlib through Turkey's Cilvegozu border gate for the treatment in the Reyhanli district of Turkey's southern Hatay Province.
"We are doing our best but that's not enough," he said. "They are our kids, our brothers. I am sad as a father."