BEIRU (AFP) - The Islamic State in Iraq and Syria (ISIS) group poured in reinforcements on Sunday for its nearly month-long siege of Kobane as the Syrian town's Kurdish defenders kept up their high-profile resistance.

ISIS has sustained serious losses in the battle for the town despite their superior armour, with at least 36 of its fighters killed on Saturday alone, the Syrian Observatory for Human Rights reported.

With the world's press massed just across the nearby border with Turkey, the fight for the town has become one the Islamists cannot afford to lose, the Britain-based monitoring group said.

"It's a decisive battle for them," Observatory director Rami Abdel Rahman told AFP.

"If they don't pull it off, it will damage their image among Islamists around the world." Abdel Rahman said that ISIS was sending additional fighters from other areas it controls in Syria, including its Euphrates Valley stronghold of Raqa, after its Friday capture of the Kurdish command headquarters in Kobane failed to deliver a decisive blow.

"They are sending fighters without much combat experience," said Abdel Rahman, whose group has a wide network of sources inside Syria.

"They are attacking on multiple fronts but they keep being repulsed, then countering and being pushed back again."