Islamic State fighters advanced deeper into the Syrian city of Kobane on the Turkish border on Friday, taking almost complete control of an area where the local Kurdish administration is based, a group monitoring the violence reported.

"They have taken at least 40 percent (of the city)," Rami Abdulrahman, who runs the Syrian Observatory for Human Rights, said by telephone.

Islamic State fighters were now in almost complete control of the "security quarter", which is home to the administrative buildings used by the local government, he said.

A Kurdish military official speaking from Kobane, also known as Ayn al-Arab, said there was fighting between Islamic State and Kurdish fighters next to a building used by Kurdish internal security forces, but denied any major advance by the group.

The new UN envoy to Syria said at least 500 civilians trapped in Kobane and besieged by the Islamic State group could be "massacred" if it falls to the extremists.

Staffan de Mistura said in Geneva on Friday that a UN analysis showed that only a small portion of Kobane remained open for people to enter or flee the city.

Mistura said there were about 500 to 700 elderly people and other civilians still trapped in the town, while 10,000 to 13,000 are stuck in an area nearby, close to the Syria-Turkey border.

He said that if the town falls to Islamic State fighters, the civilians in Kobane "will be most likely massacred".

In Turkey, the fate of Kobane sparked violence this week in more than a third of the country's provinces, leaving 31 people dead, Interior Minister Efkan Ala told a news conference.

AP - Reuters