Syrian government forces on Wednesday closed in on a rebel-held town in Idlib that was bombed with sarin in 2017, sources on both sides said, building on their Russian-backed gains since the collapse of a ceasefire this month.
The advance towards Khan Sheikhoun threatens to encircle the last remaining pocket of rebel-held territory in neighbouring Hama province, including the towns of Morek, Kafr Zeita and Latamneh.
Russian-backed Syrian government forces seized new positions from rebels to the west of the town of Khan Sheihkoun, rebel sources and state media said. A rebel commander said the town, in opposition hands since 2014, was in "great danger".
Government forces were now 4 km (2.5 miles) from Khan Sheikhoun, Rami Abdulrahman, director of the Syrian Observatory for Human Rights, said.
The sarin gas attack on Khan Sheikhoun in 2017 killed dozens of people and prompted President Donald Trump to order a missile strike against the Syrian air base from where the United States said the attack had been launched.