The British government sent the United Nations a letter reportedly detailing three additional cases of chemical weapons use in Syria, according to Bloomberg.
Britain's foreign office released a statement Wednesday saying: “The UK is extremely concerned about the ongoing allegations of chemical-weapons use in Syria,” specifying that the “allegations relate to incidents which reportedly took place in March and April this year."
US President Barack Obama has stated before that any violation of the international ban on chemical weapons in Syria would cross a "red line," hinting that such use could open the door to US intervention in a war that has claimed tens of thousands of lives over the last two years as government forces battle armed rebels.
Syrian President Bashar al-Assad has refused to allow a UN team into the country to investigate the claims, even though it was his government that originally demanded the UN's help in settling a dispute on the reported use of chemical weapons at a small village on March 19.
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At the time, the regime and rebels traded accusations amid mounting evidence of chemical warfare at the village of Khan al-Assad, but other reports have also claimed chemical weapon activity elsewhere in the country.
UN Secretary-General Ban Ki-moon wants to investigate not just one village, but the entire country.
London sent a letter to Ban last week that reportedly contained "details of new incidents since April," one diplomat told Agence France-Presse.
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Britain's UN Ambassador Mark Lyall Grant confirmed that notification was sent to the UN last week, according to the Associated Press. Ban has tasked Swedish chemical weapons specialist Ake Sellstrom to head the UN probe if and when Assad allows them entry.
"We continue to inform the secretary-general and Mr. Sellstrom of any information as and when we get it," Lyall Grant said.
Syria's splintered rebel movement is represented abroad by an opposition coalition that has since struggled to unite. On Wednesday, the group announced it will not attend an upcoming peace conference arranged by the US and Russia unless a deadline has been established for Assad to relinquish power, reported Al Jazeera.
Also Wednesday, Assad's forces took over an air base near Qusayr, where they had been fighting the rebels, according to state media cited by Reuters.
Meanwhile, the UN human rights council condemned Assad's regime of using of foreign fighters in Qusayr, according to the BBC. Fighters from Lebanon's Shia militant and political group Hezbollah have been crossing the border into Syria to fight with Assad's forces.
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