Syria's army has pushed into Raqqa province, home to the de facto capital of Islamic State, after a major Russian-backed offensive a human rights monitor says.
The Syrian Observatory for Human Rights said the offensive was the third big assault on the self-proclaimed caliphate in recent days.
Iraqi forces attempted to storm Falluja in central Iraq and a Syrian militia advanced with United States support towards Manbij in the north near the Turkish border.
The offensives were 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.
In Friday's assault the army reached the edge of Raqqa province after heavy Russian air strikes hit Islamic State-held territory in eastern areas of neighboring Hama 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.
State media said on Friday the army had made territorial gains and inflicted heavy casualties on the militants.
The Syrian army was not immediately available for comment.
State media gave no indication of how many troops were involved in the offensive, or what weapons 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.
The war monitor said the army advance meant it was now almost 40km from an area in which US-backed rebels were also waging an offensive to isolate the militants' strongholds in northern Aleppo from their territories east of the Euphrates river, where Raqqa city is located.
If the army is able to reach the area where the rebels are also fighting Islamic State, that would leave the group hemmed in, albeit by forces on opposing sides in the multi-faceted conflict who would be highly unlikely to work together.