Syrian government forces have launched a counter-attack to recapture a gas field seized by Islamic extremists, activists said Saturday, as the death toll from three days of fighting there rose to more than 200 people killed.

The intense fighting in the Shaer field, which lies in the desert region of Palmyra in the central province of Homs, has been among the deadliest battles between government forces and the Islamic State group since the start of the Syrian uprising more than three years ago.

Fighters from the Islamic State group have in the past few weeks seized a huge chunk of territory straddling the Iraq-Syria border, where they declared a self-styled caliphate. They also have captured much of Syria’s oil-rich eastern province of Deir el-Zour. […]