Russia on Sunday said it launched airstrikes on Syrian "terrorist" groups it accused of carrying out a chlorine attack on Aleppo the previous day.

"As a result of the strikes, all of the rebel fighter targets were destroyed," the TASS state news agency reported, citing Defense Ministry spokesman Igor Konashenkov.

The Britain-based Syrian Observatory for Human Rights said multiple aerial bombardments hit the edges of the last opposition Idlib bastion on Sunday.

Strong side effects reported

More than 100 people were treated for symptoms including breathing difficulties and blurred vision in Aleppo after rebels fired shells into two regions of the city, state media said.

Syrian officials and residents suspect the shells contained poisonous gas, with symptoms suggesting chlorine, according to medical official Haj Taha.

A doctor told Syrian state TV that at least two people, including one child, were in critical condition.

In a statement, Syria's Foreign Ministry on Sunday called on "the [UN] Security Council to immediately and strongly condemn these terrorist crimes ... (and take) deterrent, punitive measures against the nations and regimes that support and fund terrorism."

Read more: Pro-Turkey rebels refuse to disarm in Idlib buffer zone

Rebels reject accusations as 'lies'

Witnesses reported a smell of toxic gas after the projectiles hit, which was also confirmed by the Observatory.

"There are often missiles on the city but this is the first time we smelled such a smell," a patient told state TV while at the hospital.

The battle for Aleppo Aleppo before the war Bashar al-Assad's father, Hafiz al-Assad ruled the country with an iron grip and draconian state of emergency laws. Many experts believed that after Hafiz handed over the reins to his son Bashar, the latter would pave the way for a "Damascus spring" and usher in political and economic reform.

The battle for Aleppo 2011: Violence breaks out But instead, Bashar chose to stick to the old by suppressing the opposition with the help of Syria's dreaded security forces. His repressive leadership came under heavy pressure as it tried to stifle growing protests among its population with a brutal crackdown.

The battle for Aleppo 2012: Rebels take parts of Aleppo In early 2012, rebels took control of the rural areas northwest of Aleppo. Protesters were shot at for the first time in July and rebels started to fight for the city itself. Poorer eastern districts quickly fell to the insurgents.

The battle for Aleppo 2013: Rebel gains People ran for their lives upon hearing a nearby plane dropping bombs during a protest against President Assad in the al-Katerji Tariq district in Aleppo February 22, 2013. After losing the international highway between Hama and Aleppo, the government fought to keep alternative supply lines south of Aleppo accessible.

The battle for Aleppo Umayyad Mosque destroyed In April 2013, the minaret of Aleppo's Umayyad Mosque, which was built between the 8th and 13th centuries, collapsed after being struck during fighting. After nine months of fighting that devastated many districts in Aleppo, rebels controlled more than half of the city.

The battle for Aleppo Suffering citizens and first barrel bombs A father mourns the death of his two children. The western, government-held half of Aleppo comes under almost complete siege as rebels briefly cut the alternative route. The first barrel bombs were dropped on Aleppo in December 2013.

The battle for Aleppo 2014: Rebels and government both consolidate positions Members of the Civil Defence rescue children in the al-Shaar neighborhood of Aleppo, June 2, 2014. The government's control of the skies starts to show as it increasingly uses jets and helicopters to strike rebels.

The battle for Aleppo 2015: Massive rebel gains and Russian intervention A general view shows a damaged street with sandbags used as barriers in Aleppo's Saif al-Dawla district, March 6, 2015. A series of rebel advances put the government under pressure in northwest Syria.

The battle for Aleppo Putin meets Assad in Moscow Russian President Putin and Syrian President Assad met in Moscow, October 20, 2015. Soon after, the first Russian air strikes took place. Although Russia announced that its air force was ready to provide support to the Free Syrian Army in its fight against the "Islamic State", Russian Foreign Minister Lavrov also stressed that his forces were still backing Assad.

The battle for Aleppo 2016: The siege and bombardment of Aleppo Syrians reaching out for Russian food aid. The text on the bag, which shows the Syrian and Russian national flags, reads: "Russia is with you". In July, government forces fully encircled eastern Aleppo for the first time. The siege was broken ten days later by a rebel counterattack.

The battle for Aleppo Evacuation of Aleppo After months of intense bombardment in which many hospitals were hit, the Russian and Syrian governments urged rebels and civilians to evecuate east Aleppo. On December 13, insurgents agreed to withdraw in a ceasefire deal. The evacuation began the next day. Author: Nadine Berghausen



Rebels around the city rejected Russian claims that they had fired shells filled with chlorine. Rebel commander Abdel-Salam Abdel-Razak, who once served in Syria's chemical weapons' program, said the militants did not have gas-based ammunition or the capability to launch gas-filled shells.

"These are lies," Abdel-Razak tweeted in response to reports of a rebel gas attack.

War returns to Aleppo

Aleppo was retaken by government forces in 2016, following years of siege. Despite a subsequent truce brokered by Turkey and Russia, rebels have intensified their shelling of the city in recent weeks. The government has responded by launching attacks on rebel positions elsewhere in Aleppo province.

Read more: As civilian evacuation ends, Syrian army 'reclaims' Aleppo

Watch video 01:41 Share Aleppo: Getting better, but a long way to normal Send Facebook google+ Whatsapp Tumblr linkedin stumble Digg reddit Newsvine Permalink https://p.dw.com/p/2ZJcC Aleppo: Getting better, but a long way to normal

The government and the numerous rebel factions have traded accusations of chemical weapons use since the conflict broke out in 2011. Last year, a suspected government attack killed around 100 people in the town of Khan Sheikhoun prompting the US to fire Tomahawk missiles at Syrian government forces. This strategy was repeated following the Douma chemical attack in April, also blamed on the Syrian government.

mm, dj/rc (AP, Reuters, Interfax)

Each evening at 1830 UTC, DW's editors send out a selection of the day's hard news and quality feature journalism. You can sign up to receive it directly here.