An aid convoy meant to provide relief supplies to civilians trapped in Syria’s Eastern Ghouta enclave was stopped on Thursday amid reports of a chlorine attack in the region. “The convoy for today is postponed as the situation is evolving on the ground, which doesn’t allow us to carry out the operation,” a spokesperson for the International Committee of the Red Cross, Ingy Sedky, told AFP.

The convoy, jointly operated by the Red Cross, the Syrian Arab Red Crescent organisation and the United Nations, was expected to deliver aid to Eastern Ghouta’s main town of Douma on Thursday. But its trucks remained parked at the Syrian government-controlled Wafideen checkpoint on the edge of Eastern Ghouta.

Rescue workers and Opposition activists in the enclave accused Syrian forces of a chlorine gas attack in Saqba and Hammouriyeh on Wednesday night, Reuters reported. The previous day, doctors and medics in rebel-held Eastern Ghouta reported a suspected chlorine strike, allegedly by forces loyal to Syrian President Bashar al-Assad. A group of search and rescue workers called the White Helmets tweeted that 30 cases of suffocation were reported after the attack in Hammouriyeh city.

In the past 18 days, 898 people have died in the air and ground offensives carried out by government forces in Eastern Ghouta to fight the rebels, according to the Syrian Observatory for Human Rights.

A convoy of 46 aid trucks crossed the Wafideen checkpoint on Monday, but Syrian government authorities reportedly confiscated surgical kits, insulin, dialysis equipment and other medical supplies from the vehicles.

Meanwhile, an unidentified Syrian Army commander said government forces would soon “slice” the Eastern Ghouta enclave into two, Reuters reported. But Wael Alwan, a Turkey-based spokesperson for the rebel Failaq al-Rahman group, denied that the enclave had been split.

Hussam Aala, Syria’s ambassador to the United Nations, told the Human Rights Council that military operations in eastern Ghouta targeted “terrorist organisations in accordance with international humanitarian law”.