AIR strikes on Syria have killed more than 500 people, mainly Islamic militants, since they began last month, activists have said as fighting flared yesterday in the northern Syrian border town of Kobani.

The Syrian Observatory for Human Rights, which relies on a network of activists on the ground, said 553 people have been killed since the air strikes began on September 23, including 32 civilians.

The civilians included six children and five women.

The group said it has documented the deaths of 464 Islamic State (IS) fighters adding that the real number could be much higher.

Another 57 fighters with the al Qaida-linked Nusra Front were killed in air strikes on the northern province of Aleppo and Idlib, the Observatory said.

Many of the IS fighters have been killed in or near Kobani, the target of a massive jihadi offensive since mid-September.

IS fighters have captured dozens of surrounding Kurdish villages and forced more than 200,000 people to flee for safety in Turkey.

The US Central Command said its forces had conducted more than 135 air strikes against Islamic State militants in and around Kobani.

It said: "Indications are that these strikes have slowed Isil advances, killed hundreds of their fighters and destroyed or damaged scores of pieces of Isil combat equipment and fighting positions."