A new team established by the global chemical weapons watchdog to attribute blame for the use of banned munitions in Syria will investigate

Western states have warned that Syria could be violating a ban on chemical weapons, during a meeting of the executive council

Syrian officials have refused access to a newly-created chemical weapons investigation team formed to identify culprits behind attacks with banned munitions, the organisation's top official said in remarks published on Wednesday.

US National Security Advisor John Bolton warned the Syrian government that it should not see the impending US military withdrawal from the country as an invitation to use chemical weapons.

The global chemical weapons agency will investigate an alleged gas attack in Syria's Aleppo that reportedly wounded up to 100 people on Saturday, the agency's chief said on Monday.

France's top military official said on Thursday his forces were prepared to carry out strikes on Syrian targets if chemical weapons were used in an expected government offensive to retake the northern province of Idlib.

The United Nations called on Russia, Iran and Turkey on Thursday to forestall a battle in Syria's Idlib province which would affect millions of civilians and could see both sides using chlorine as a chemical weapon.

Inspectors with the global chemical weapons agency on Wednesday visited a second site in Syria's Douma and took samples to help them determine whether banned toxic munitions were used there.

A team of inspectors from the Organisation for the Prohibition of Chemical Weapons (OPCW) visited a site in Douma, Syria on Saturday to collect samples as it tries to determine whether such weapons were used there on April 7, the agency said.

Chemical weapons inspectors had to delay visiting the site of an alleged chemical weapons attack in Syria's Douma on Wednesday after a UN security team reported gunfire at the location a day earlier, sources briefed on the team's deployment told Reuters.

Russia may have tampered with the site of an alleged chemical weapons attack in Syria's Douma, the US envoy to the global watchdog said on Monday, urging the body to condemn the continuing use of banned chemical weapons.

British had no alternative but to take military action to degrade Syria's chemical weapons capability, Prime Minister Theresa May said on Saturday after ordering air-launched cruise missile strikes along with the United States and France.