The Islamic State launched a fresh assault on Kobane late Monday hours after it was announced that Kurds, who are defending the besieged Syrian border town, had received a first US airdrop of weapons.

The fighters had launched an assault "on all fronts of the city," Rami Abdel Rahman, the director of the Syrian Observatory for Human Rights monitoring group told AFP.

There were reports of heavy fighting in Kobane in the evening.

The assault followed two suicide attacks in the north of Kobane earlier on Monday, in an apparent bid to cut the town off from Turkey.

And fighters also sent in reinforcements from Jarabulus to the west of Kobane, as shelling of the centre of town resumed towards the end of a relatively calm day.

It came as IS appeared to have opened up another front in Iraq with an attack on the Kurdish-controlled town of Qara Tapah that killed 10 people and sparked an exodus of half its population of 9,000.

"We are afraid IS will encircle us and turn this town into a second Amerli," said a resident of Qara Tapah who gave his name as Haidar, in reference to a majority Turkmen Shiite town farther north that was besieged by IS for two months.

The renewed fighting came after increased activity on the diplomatic front.

As well as the air drops, Turkey said on Monday it would help support Iraqi Kurds.

Ankara has refused land deliveries of arms to the Syrian Kurds, who are linked with Turkey's outlawed rebel Kurdistan Workers' Party (PKK), but said it was helping Iraqi Kurds to reinforce the strategic town in a reversal praised by Washington.

The Syrian Kurdish forces in Kobane hailed the airdrop, saying it would "help greatly" in the town's defence against a nearly five-week IS offensive.

US Secretary of State John Kerry said it would have been "morally very difficult to turn your back on a community fighting ISIL," using another acronym for IS.

And a senior administration official said the airdrop was in recognition of the "impressive" resistance put up by the Kurds and the losses they were inflicting on IS.

Three C-130 cargo aircraft carried out what the US military called "multiple" successful drops of supplies, including small arms, provided by Kurdish authorities in Iraq.

The supplies were "intended to enable continued resistance against ISIL's attempts to overtake Kobane," said US Central Command.

'We thank America'

The US-led coalition has carried out more than 135 air strikes against IS targets around Kobane, but this was the first time it had delivered arms to the town's defenders.

"The military assistance dropped by American planes at dawn on Kobane was good and we thank America for this support," said Redur Xelil, spokesman for the Syrian Kurdish People's Protection Units (YPG).

"It will have a positive impact on military operations against Daesh and we hope for more," he added, using the Arabic acronym for IS.

Xelil declined to detail the weapons delivered but said there was "coordination" over the drop.

IS launched its Kobane offensive on September 16, swiftly pushing Kurds back to the town itself and sparking an exodus of 200,000 refugees into Turkey.

But the Kurds have kept up a dogged resistance on the streets of the town, of which they control around half.

Turkey offer of help

Ankara has kept the YPG at arms length because of its links to the PKK, which has waged a three-decade insurgency for Kurdish self-rule in southeast Turkey that has left some 40,000 people dead.

But Foreign Minister Mevlut Cavusoglu said Turkey was now helping Iraqi Kurdish peshmerga forces to bolster the fight in Kobane.

"We are assisting peshmerga forces to cross into Kobane," he said. "We have no wish at all to see Kobane fall."

With the shift in Turkish strategy, US State Department deputy spokeswoman Marie Harf said: "We welcome those statements from the foreign ministry".

The European Union, meanwhile, urged "Turkey to open its border for any supply for the people of Kobane," in a statement after a meeting of its foreign ministers.

The YPG said no peshmerga had yet arrived in Kobane, while the Iraqi peshmerga said Syrian Kurds trained in northern Iraq would be sent in but not Iraqi Kurds.

But despite carrying out its first airdrops in Kobane, the US military says its top priority remains Iraq, where IS swept through much of the Sunni Arab heartland north and west of Baghdad in June.

Since last week, the Iraqi capital has seen a rise in the number of bomb attacks, several of which have been claimed by the Sunni extremist IS.

And on Monday a suicide bomber detonated explosives outside a Shiite mosque in the central Baghdad neighbourhood of Sinak, killing at least 11 people.

The violence has raised fears IS will attack large gatherings of Shiite worshippers during the upcoming Ashura commemorations, the target of devastating bombings in past years.