Syrian Kurdish fighters have seized dozens of villages from Islamic State group jihadists around the town of Kobane on the Turkish border, expanding their control in the area, a monitor said Friday.

The Kurdish People's Protection Units (YPG) had captured 101 villages around Kobane since seizing it from IS on January 26 after four months of fighting, the Syrian Observatory for Human Rights said.

"They now control territory ranging from 15 to 25 kilometres (nine to 16 miles) from Kobane to the east, west and south," Observatory director Rami Abdel Rahman said.

The small town became a key battleground, with IS poised at one point to overrun it and cement its grip on a large stretch of territory along the border.

Since January 26, YPG forces have advanced steadily in the surrounding countryside, recapturing dozens of villages, some no larger than a few dozen homes.

In some villages, they have met little resistance, with IS fighters withdrawing as they advance.

But in other places there have been clashes, with the Observatory saying at least 13 IS fighters were killed in a YPG ambush Friday.