The Syrian Observatory for Human Rights on Wednesday reported that warplanes had again launched air strikes on opposition-held Khan Shaykhun in Idlib province.
SOHR reported that five air strikes had hit the area, but did not identify the number of fatalities, injuries or which warplanes were involved.
Regime air strikes on Tuesday and a suspected chemical or nerve agent attack killed more than 70 people, including 20 children and 17 women.
SOHR said those killed had died from suffocation and the effects of a toxic gas.
Citing medical sources who described the air strikes as a "toxic gas attack," SOHR reported that many people had choked or fainted, and some had foam coming out of their mouths.
On Wednesday, the US government said it believed the potent nerve agent sarin was used in the attack.
It also said the attack was "almost certainly" carried out by forces loyal to regime leader Bashar al Assad.
Turkey's Health Ministry on Wednesday said its findings indicated a chemical attack.
Health Minister Recep Akdag made the announcement, a day after Turkey ferried 30 victims of the assault across the border for treatment.
TRT World's Ediz Tiyansan spoke with some of them at a hospital near the Turkish-Syrian border.
Russia blames opposition
On Wednesday, Russian Defence Ministry spokesman Igor Konoshenkov said the regime hit a rebel chemical weapons depot.
"From 11:30am to 12:30pm local time, Syrian aviation made a strike on a large terrorist ammunition depot and a concentration of military hardware in the eastern outskirts of Khan Shaykhun town," Konoshenkov said.
"On the territory of the depot, there were workshops which produced chemical warfare munitions."
But the opposition has vehemently denied the claims, labelling them "lies."
Syrian rebel commander of the Free Idlib Army Hasan Haj Ali, said no opposition military positions in the area were targeted on Tuesday.
"Everyone saw the plane while it was bombing with gas," he said.
"Likewise, all the civilians in the area know that there are no military positions there, or places for the manufacture [of weapons]. The various factions of the opposition are not capable of producing these substances."
On Tuesday, Idlib's Health Authority pointed towards a potent nerve agent which was dropped from warplanes.
"This morning, at 6:30am, warplanes targeted Khan Shaykhun with gases, believed to be sarin and chlorine," said Mounzer Khalil, head of Idlib's health authority.
Later on Tuesday, warplanes later struck near a medical point where victims of the attack were receiving treatment, SOHR and civil defence workers said.
TRT World's Sally Ayhan reports.
The United Kingdom said on Wednesday that all evidence points to Assad to be behind Tuesday's attack.
US President Donald Trump also condemned the "heinous actions by the Bashar al Assad regime," blaming his predecessor Barack Obama's "weakness" on Syria.
Israeli Prime Minister Benjamin Netanyahu on Tuesday condemned the incident as well.
But, the UN's spokesperson said the reports are yet to be confirmed.
Stéphane Dujarric, spokesperson for the UN Secretary-General, added that the Organisation for the Prohibition of Chemical Weapons had begun collecting and analysing the relevant information about the use of chemical weapons in Syria.
Representatives from the UN, the EU and countries around the world, arrived in Brussels on Wednesday for a meeting on rebuilding Syria.
EU Foreign Affairs Chief Federica Mogherini urged the international community to press ahead with the Syria peace talks.
"We need to give a push, a strong push to the political talks in Geneva. We have to unite the international community behind these negotiations," Mogherini said as she went into a Syrian aid conference in Brussels.
"The horrific events of yesterday demonstrate unfortunately that war crimes are going on in Syria [and that] international humanitarian law is being violated frequently," UN chief Antonio Guterres said as he entered the conference in Brussels.
In New York, the UN Security Council is to due hold emergency talks following the attack.
The US, Britain, and France on Tuesday proposed a UN Security Council resolution condemning the attack.
The Syrian military denied responsibility and said it would never use chemical weapons.