US warplanes struck 14 times near Kobane into Thursday, hammering the Islamic State militants besieging the key Syrian border town, the American military said.

Central Command said the air attacks Wednesday and Thursday "successfully struck" 19 IS-held buildings, two command posts, a heavy machine gun, three sniper positions and other targets.

US-led forces have now carried out more than 100 air strikes near Kobane since September 27, according to Central Command figures.

The latest bombing raids came as Kurdish forces continued to hold out against an IS offensive around Kobane, and with much of the world's media focused on the fate of the town.

US military officers say the town may eventually fall but insist Kobane is not a "strategic" location and that other areas carry more importance, particularly in western Iraq and the suburbs of Baghdad.

But they privately acknowledge that intense media coverage, with television cameras across the border in Turkey relaying footage of smoke rising from the town, have turned Kobane into an important symbol.

As the tempo of air strikes dramatically increased this week, Pentagon spokesman Rear Admiral John Kirby said on Wednesday the raids had killed "several hundred" fighters from the IS group near the town.

And a Kurdish official in Kobane said the militants had been rolled back from parts of the town.

Amid concern over IS gains in Anbar province in western Iraq, the United States and its allies are also striking the IS group in Iraq.

But bad weather has hampered the air campaign in the area the past few days, Kirby said.