Syrian Kurdish fighters said they had fully secured the town of Kobani near the Turkish border on Saturday and killed more than 60 Islamic State militants, two days after the hardline group launched an incursion with suicide bombers.
Further east, Islamic State pressed another assault on government-held areas of Hasaka city, clashing with the Syrian army after blowing up a security building late on Friday and triggering a government appeal for residents to take up arms.
"The people of the governorate and its surroundings continue to sign up with the Syrian Arab Army in its fight against terror," state television said in a news flash on Saturday and played archive footage of soldiers set to rousing music.
Hasaka's governor described the situation as "fine" but also called on residents to defend it in a phone call with state TV.
The twin assaults on Kobani and Hasaka came after Islamic State suffered two weeks of defeats at the hands of Kurdish-led forces, supported by US-led air strikes.
Redur Xelil, spokesman for the Kurdish YPG militia, said Kobani was quiet and the YPG was combing the town for any hidden Islamic State fighters.
The YPG blew up a school building used by Islamic State in the town earlier on Saturday, the Syrian Observatory for Human Rights monitoring group said, and plumes of smoke could be seen from the Turkish side of the border rising into the air.
The Observatory said a U.S-led airstrike killed at least 18 Islamic State fighters near Kobani. Islamic State killed around 200 civilians since the assault which started on Thursday, the Observatory said, describing it as one of the worst massacres committed by the group in Syria.
BATTLE FOR HASAKA CITY
In Syria's northeast, Kurdish forces and the army fought separate battles with the group around the city overnight. The YPG's Xelil said the Kurds were not fighting with Islamic State on Saturday.
The Observatory said fierce battles continued in the southwest, south and southeast on Saturday.
Islamic State launched its offensive on government-held areas of Hasaka on Thursday and the United Nations says the violence is estimated to have displaced up to 120,000 people.
"We want to reassure people in the governorate...Hasaka is fine," Governor Mohammad Zaal al-Ali told state TV but also echoed a government call for people to come back and defend their homes alongside the army.
"All of the people of the governorate who want to, pick up arms to defend it," he added. He said the air force had been carrying out frequent bombardments against Islamic State.
Hasaka province is important because it sits between Islamic State-held territory in Syria and Iraq and reaches north to the Turkish border. The city is divided into areas run separately by President Bashar al-Assad's government and Kurdish authorities.
The assault will test the army's capacity to hold on to areas far from the major government-held cities in the west. The YPG, which controls northern parts of the city, says it does not cooperate with government forces.
Islamic State said in statements posted online on Saturday it had attacked areas east of the city and in a video posted on YouTube said it had entered western areas.
Late on Friday Damascus called on Hasaka residents to take up arms in defence.
"I call on every man, every young woman and every young man able to carry weapons to move immediately and join the frontline positions to defend the city," Syrian Information Minister Omran al-Zoubi said on state television.