The government and opposition forces in Syria have accused each other of using poison gas in an attack on a village on Friday, BBC reported.
State TV said the jihadist Nusra Front group launched the attack on Kafr Zita in Hama province, killing two people and injuring dozens of others.
But opposition groups quoted doctors as saying that an attack by regime planes led to suffocation and poisoning.
There was no independent verification of either of the claims.
"Regime planes bombed Kafr Zita with explosive barrels that produced thick smoke and odours and led to cases of suffocation and poisoning," said Rami Abdel Rahman, from the Syrian Observatory for Human Rights.
State-run television blamed the attack on the Nusra Front and said they had information that the jihadist group was planning to attack two more towns.
"There is information that the terrorist Nusra Front released toxic chlorine... leading to the death of two people and causing more than 100 people to suffer from suffocation," it said.
In a separate incident, the Al-Arabiya TV news network also reported on Friday that there were a number of cases of suffocation in Harasta, a northeastern suburb of Damascus.
An opposition group was quoted by the news channel as saying the incident came "after the regime bombarded it with poisonous gas."
In August last year, a chemical attack near the capital killed hundreds of people.
The US and its allies blamed the Syrian government for that attack, which nearly sparked Western airstrikes against President Bashar Assad's forces.
The government denied responsibility, in turn blaming the rebels, but Damascus agreed under threat of US military action to turn over its chemical weapons stockpile for destruction.