Russia has lambasted the United States over its support for Takfiri militant groups that launch toxic gas attacks against civilians in Syria, referring to the militants as "animals."

“The United States is supporting these animals, who used poison gas against the civilian population,” Russian Foreign Ministry spokeswoman Maria Zakharova wrote in a statement posted to social media on Thursday.

She added, “Unfortunately it's not the only tragedy which the 'moderates' backed by Washington stand behind.”

Zakharova was making reference to Tuesday’s chemical attack by US-backed Takfiri militants in the Old City of Aleppo, where artillery shells containing toxic gasses slammed into a residential neighborhood.

At least seven people died and 20 others sustained injuries in the shelling.

On Wednesday, Lieutenant-General Sergey Chvarkov, the director of the Russian Reconciliation Center in Syria, said Moscow had warned Washington about the use of toxic shells by the US-backed ‘moderate’ militant group a day prior to the attack.

The Russian diplomat further held the Nour al-Din al- Zinki terror outfit responsible for the recent chemical attack in the Salaheddine district of Aleppo.

A man receives treatment at a hospital following a Daesh chemical attack in the Sheikh Maqsood neighborhood of Syria’s northwestern city of Aleppo, April 7, 2016.

Members of the militant group are already involved in the beheading of a 12-year-old Palestinian boy, named Abdullah Tayseer al-Issa, in northern Aleppo.

The terrorists initially claimed in a video that the child had been fighting for the Syrian government in Aleppo, thought it was later revealed that the victim was a kidnapped Palestinian refugee from a poor family.

Zakharova also accused the US Air Force of indiscriminately bombing inhabited parts of the town of Ghandour, which lies more than 23 kilometers (14.2 miles) away from the violence-ridden city of Manbij, on July 28. At least 28 people, including seven children, lost their lives and dozens of others sustained injuries.

“If our Western colleagues and above all Washington do everything again not to notice these facts, then any of their talk about an end to bloodshed in Syria will simply become preposterous,” the Russian foreign ministry spokeswoman pointed out.

The US-led coalition has been conducting airstrikes against what are said to be Daesh positions inside Syria since September 2014 without any authorization from Damascus or a UN mandate.

The coalition has repeatedly been accused of targeting and killing civilians. It has also been largely incapable of fulfilling its declared aim of destroying Daesh.