Kurdish fighters reportedly ousted the Islamic State group from the Syrian border town of Kobane on Saturday, two days after the jihadists seized several neighbourhoods, a monitoring group said.

"The Kurdish People's Protection Units (YPG) took back control of IS positions in Kobane," the Syrian Observatory for Human Rights said.

Kurdish activist Rudi Mohammad Amin said that "all of Kobane is again under the control of the YPG," adding that "a number of IS fighters were killed and wounded".

IS is reported to have killed at least 145 people in and around Kobane in what the Observatory has described as one of the worst massacres carried out by Islamic State in Syria.

The killings took place mostly inside Kobane itself, and were widely seen as vengeance for a series of defeats inflicted on the jihadists by Kurdish militia in recent weeks.

The militants reportedly launched repeated attacks on the town over a 24-hour period.

Residents say almost no-one was spared.

"They entered town by disguising themselves as Kurdish fighters," Syrian Kurd Halil Hadi said.

"They slaughtered children even toddlers who were one year old. Nobody could tell they were Islamic fighters, and they were even speaking our language. They arrived in our town in cars and killed everyone."

The British-based Syrian Observatory for Human Rights — which claims to have a network of activists on the ground in Syria who monitor the civil war — said the bullet-riddled bodies of 18 people, including children, were found on Friday in the streets of Kobane.

It appeared they had been shot "at close range".

"The body of one child bore the impact of five bullets," the observatory said.

Civilians taken hostage, used as human shields: monitor

Kurdish journalist Mostafa Ali said there was no military dimension to the assault.

"IS doesn't want to take over the town; they just came to kill the highest number of civilians in the ugliest ways possible," he said.

Kurdish activist Arin Shekhmos said: "Every family in Kobane lost a family member on Thursday."

The jihadists entered Kobane at dawn on Thursday disguised as YPG fighters, Mr Ali said, taking up positions in buildings in the south of the town, using civilians as "human shields".

More than 1,000 fleeing civilians waited on the Syrian side of the frontier with Turkey on Friday, carefully watched by Turkish troops and police.

Kobane was the scene of one of IS' most dramatic defeats when Kurdish militia backed by US-led air strikes ousted the jihadists in January after four months of heavy fighting.

IS has hit back against Kurdish victories with an offensive against Hasakeh in the northeast, capital of the mainly Kurdish province of the same name.

Pictures posted online by IS show what appear to be soldiers' bodies as well as weapons and ammunition.

On Thursday, the UN Office for the Coordination of Humanitarian Affairs said the Hasakeh clashes had displaced an estimated 60,000 people.

The jihadists previously advanced to the southern edge of Hasakeh in May but were pushed back by government forces.

Information minister Omran Zohbi urged "anyone who is capable of carrying a gun" to "protect Hasakeh", the official SANA news agency reported.

In southern Syria, a rebel alliance has been pressing an assault since Thursday on the city and provincial capital of Deraa that has killed 70 people, 40 of them rebels, said the Observatory.

The Syrian government has already lost two provincial capitals in the four-year-old civil war: IS-held Raqa in the Euphrates valley and Idlib in the northwest, which is held by a rebel alliance including Al-Qaeda.

At least 230,000 people have been killed since Syria's conflict erupted in 2011 in Deraa.

AFP/Reuters