Over 100 people were hurt in a suspected gas attack that Syria and Russia blamed on rebels (AFP)
The United States has warned Russia and Syrian President Bashar al-Assad's government against tampering with the site of an alleged chemical weapons attack in Aleppo, saying it has information that the parties manufactured last month's incident to discredit a ceasefire in Idlib.
In a statement Friday, the US State Department said the Syrian government and its ally, Russia, have "falsely accused the opposition and extremist groups of conducting a chlorine attack" in northwestern Aleppo on 24 November.
"The United States strongly refutes this narrative and has credible information that pro-regime forces likely used tear gas against civilians," the department said.
Last month, more than 100 people were wounded in Aleppo in a suspected toxic gas attack that the Syrian government and Russia blamed on rebels.
A health official in Aleppo said at the time that victims suffered breathing difficulties, eye inflammation and other symptoms that suggested the use of chlorine gas.
Officials with Syrian rebel groups denied the allegations, however, and said their forces did not possess chemical weapons.
On Friday, the US said pro-government officials have kept control of the attack site, "allowing them to potentially fabricate samples and contaminate the site before a proper investigation of it by the Organization for the Prohibition of Chemical Weapons".
"We caution Russia and the regime against tampering with the suspected attack site and urge them to secure the safety of impartial, independent inspectors so that those responsible can be held accountable," the US State Department said.
The department also said it had "information indicating Russian and Syrian personnel were involved in the tear-gas incident, and believes that both countries are using it as an opportunity to undermine confidence in the ceasefire in Idlib".
The Syrian government and rebel groups reached a ceasefire agreement in September in Idlib, which prevented an all-out government assault on the northwestern Syrian city and averted a humanitarian crisis.
Both Syrian government forces and opposition groups fighting in Syria have been accused of using chemical weapons in the seven-year war and both sides have blamed the other for allegedly carrying out false-flag operations.