IS militants spread to Syria's Kurdish town

The Islamic State (IS) Tuesday spread to a southern district of the key Syria-Turkey border town of Kobane, as US-led air strikes continued pounding positions of the Sunni radical group.

The Syrian Observatory for Human Rights (SOHR) said that IS had crossed into a southern district of Kobane, taking over many buildings, BBC reported.

However many IS fighters were killed in an ambush by Syrian Kurdish fighters, SOHR said, adding that at least 400 people have been killed in three weeks of fighting for Kobane.

Fighter jets from the US-led coalition were reported to have conducted further strikes Tuesday morning, though the targets were unclear.

IS fighters entered the town's three eastern districts Monday, raising their black flag on buildings and hills.

Turkish President Recep Tayyip Erdogan said the town was on the verge of falling and "co-operation" on a ground offensive was necessary.

If IS captures Kobane, its militants will control a long stretch of the Syrian-Turkish border.