Russia says it has sent military chemicals experts to Aleppo after reports that shells fired by insurgents in the Syrian city left dozens of people with breathing and vision problems.

Defense Ministry spokesman Igor Konashenkov said on November 25 that specialists from Russian nuclear, chemical and biological warfare protection units had arrived at the scene of the attacks after Syrian state TV broadcast footage of medics treating people for what appeared to be injuries related to the use of chemical weapons.

The rebels rejected the allegations that they had used chemical weapons on November 24, and instead accused government officials of staging the attack to undermine a cease-fire.

Around 100 Syrians were hospitalized with breathing difficulties, Syria’s state news agency SANA and a British-based monitor said.

The Syrian Observatory for Human Rights said most have been discharged and the 31 cases that remained were not critical.

Both sides in the Syrian conflict have accused each other of carrying out chemical attacks, which are difficult to corroborate in the absence of independent monitors.

Konashenkov told journalists that the Russian experts "are working with the injured in hospitals and are monitoring the environment in the area where toxic substances were used by militants."

"According to initial information, confirmed, among other things, by symptoms diagnosed in those affected, the projectiles launched at residential districts of Aleppo appear to have been filled with chlorine," he added.

The Russian Defense Ministry said the attack was launched from a "deescalation zone" in neighboring Idlib Province that is controlled by Al-Nusra Front militants.

The ministry also said it planned to talk to Turkey about the incident since Ankara is a guarantor of how the armed opposition upheld a cease-fire in the area.

Rebel commander Abdel-Salam Abdel-Razak added that opposition groups neither have weapons containing poisonous gases nor the capability to launch them.

Experts from the United Nations and the Organization for the Prohibition of Chemical Weapons (OPCW) have accused the Damascus government of using chlorine gas in at least two attacks in 2014 and 2015 and the nerve agent sarin in an attack in April 2017.

Russia, which has given Syrian President Bashar al-Assad crucial support throughout the war, has backed the government in denying it was behind chemical weapons attacks and accusing rebels of carrying them out.

The joint UN-OPCW team has also blamed the Islamic State (IS) extremist group for using mustard gas twice in 2015 and 2016.

Earlier on November 25, government shelling of a rebel-held area in Idlib Province killed at least seven civilians, including several children.

The two sides have periodically exchanged fire in northwest Syria since an accord between Moscow, a key ally of Damascus, and Turkey, which backs some rebel factions, was agreed to create buffer zones in the region to limit fighting.

The Syrian conflict began with a government crackdown on protesters in March 2011 and has left more than 400,000 people dead, displaced millions, and devastated many historic sites across the country.

With reporting by Reuters, AP, AFP, TASS and SANA