State TV said on Saturday that the extremist Nusra Front group launched the attack on Kafr Zita in Hama province, killing two people and injuring dozens of others.

Some anti-Syrian government groups claimed that an attack by government planes led to suffocation and poisoning.

State-run television said there has been information that the Nusra Front 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 channel also reported on Friday that there were a number of cases of suffocation in Harasta, a northeastern suburb of Damascus.

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 the Syrian armed forces.

The government denied responsibility, in turn blaming the foreign-backed militants and extremist terrorists, but Damascus agreed under the threat of US military action to turn over its chemical weapons stockpile for destruction.

Syria has been gripped by deadly unrest since 2011. According to reports, Western powers and their regional allies - especially Qatar, Saudi Arabia, and Turkey - are supporting the militants operating inside the country.

NTJ/HH