The Syrian army has crossed the boundary of Raqqa province, home to the de facto capital of Islamic State, after a major Russian-backed offensive against the militants, the Syrian Observatory for Human Rights said on Saturday.
The offensive is the third big assault on the self-proclaimed caliphate in recent days after Iraqi forces attempted to storm a city and a Syrian militia advanced with U.S. support.
The three big offensives are some of the most aggressive campaigns against Islamic State since it declared its aim to rule over all Muslims from parts of Iraq and Syria two years ago.
Heavy Russian air strikes hit Islamic State-held territory in eastern areas of Syria’s Hama province, near the boundary of Raqqa province, on Friday when the army reached the edge of the province.
Raqqa city, further east, is Islamic State’s de facto capital in Syria and, along with Mosul in Iraq, the ultimate target of those seeking to destroy the group.
The army was making its advances from the Athriya area of eastern Hama province, close to the provincial border with Raqqa. State media said on Friday the army had made territorial gains and inflicted heavy casualties on the militants.
Syrian army spokesmen were not immediately available for comment.
State media has given no indication of how many troops are involved in the offensive, or what weaponry they might be using.
The Observatory also had no comment about numbers or weapons, but said at least 26 Islamic States militants had been killed along with nine from the Syrian and allied forces.