BEIRUT: A US-led coalition has carried out at least 150 air strikes on the Islamic State (IS) group to back an offensive near the militants’ northern Syria stronghold, a monitor said on Friday. The coalition, as well as US special operations forces, is supporting the Syrian Democratic Forces as they advance in the northern province of Raqa. The Syrian Observatory for Human Rights said that 150 strikes had targeted IS positions around the flashpoint towns of Tal Abyad and Ain Issa since the push was launched on Tuesday. “There has been a serious intensification of air strikes, but they were most intense on the first day of the operation,” said observatory head Rami Abdel Rahman. The Britain-based observatory also said that clashes in rural territory in northern Raqa province had left at least 31 militants dead since Tuesday. “There are definitely casualties among the SDF’s ranks but they are not releasing any figures,” he said. “There are almost no civilians in the villages where the fighting is happening, which is why there is no civilian death toll.” But further south in the provincial capital of Raqa city, the militant group was blocking desperate civilians from fleeing. “Islamic State is not issuing passes to leave the city – it has even become difficult for people who are sick and need treatment elsewhere,” Rahman said. A handful of families had been able to escape the city and had made it west to Idlib province, controlled by a rebel alliance, including Al-Nusra Front.