Kurdish defenders of the strategic Syrian border town of Kobane awaited reinforcements Wednesday after weathering another onslaught by Islamic State jihadists.

Fighting appeared to have diminished after a fierce attack begun by IS fighters almost 48 hours earlier, including suicide bombers, witnesses and monitors said.

IS jihadists in east Kobane were exchanging fire with Kurdish militia in the west and there were reports of an explosion, probably a car bomb, the Syrian Observatory for Human Rights monitoring group said.

A total of 30 jihadists and 11 Kurdish fighters were killed in 24 hours, the Britain-based Observatory said late Tuesday, adding that IS was bringing in reinforcements "as a result of the daily losses in Kobane".

The town has become a crucial battleground in the war against IS, which is fighting to extend areas under its control in Iraq and Syria where it has declared an Islamic "caliphate".

The lull came as the UN accused the Islamic State of "attempted genocide" against Iraq's Yazidi minority and said atrocities committed by jihadists may amount to war crimes and crimes against humanity.

"The evidence strongly indicates attempt to commit genocide," UN Assistant Secretary General Ivan Simonovic said after meeting with officials and displaced people in Arbil, Baghdad and Dohuk during a week-long visit.

Tens of thousands of Yazidis have fled, fearing for their lives after being targeted for their religious beliefs.

- Diplomatic moves -

Against a backdrop of continued fighting, there has been feverish diplomatic efforts with Turkey announcing Monday that it would help Kurdish forces from Iraq to relieve Kobane's beleaguered defenders, in a major shift of policy that was swiftly welcomed by Washington.

Iraqi Kurdish officials have said they will provide the training, although any forces sent will be Syrian Kurds.

A local Kurdish official, Idris Nassen, told AFP on Tuesday that no reinforcements had yet arrived and they did not have "any idea" when they would.

Turkish Foreign Minister Mevlut Cavusoglu confirmed Kurdish fighters had yet to cross from Turkey to Kobane, explaining that "the issue is still being discussed".

The US administration has stepped up its commitment to Kobane in recent days, with Secretary of State John Kerry saying it would be "irresponsible" and "morally very difficult" not to help.

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

A US-led coalition has carried out more than 140 air strikes against IS targets around Kobane, but it was the first time it had delivered arms to the town's defenders.

US Central Command said one of the 27 bundles had gone astray but that American warplanes bombed it to prevent it being snatched by IS.

It also said American warplanes carried out four strikes near Kobane on Monday and Tuesday, while coalition aircraft conducted another three in Iraq.

Despite the Kobane operation, US commanders said the top priority remains Iraq, where IS swept through much of the Sunni Arab heartland north and west of Baghdad in June, with both government and Kurdish forces under pressure.

The jihadists attacked the Kurdish-controlled town of Qara Tapah on Monday, killing at least 10 people and prompting half of its 9,000 residents to flee.

"We are afraid IS will encircle us and turn this town into a second Amerli," said one resident, referring to a mainly Shiite Turkmen town further north besieged by IS for two months over the summer.

Since last week, Baghdad also seen a rise in the number of bombings, several of which have been claimed by IS.

Two car bombs exploded Tuesday in a Shiite area of the capital, killing at least 12.

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.

- Iraq PM in Tehran -

Meanwhile, Iraqi Prime Minister Haidar al-Abadi, in Iran for talks with his Shiite ally, described IS as "a threat to the entire region".

IS holds towns just a few miles (kilometres) from the Iranian border, and Tehran has been a key backer of Baghdad's efforts to hold them back.

According to a senior Iraqi Kurdish official, Iran has deployed troops on the Iraqi side of the border in the Khanaqin area northeast of Baghdad.

Iranian forces also played a role in breaking the siege of Amerli, another senior Kurdish official said.

But Abadi has ruled out any foreign ground intervention to assist government forces in retaking territory lost to jihadists.

After meeting Abadi, Iranian supreme leader Ayatollah Ali Khamenei said he believed Iraq and its government "have the capacity to overcome the terrorists and establish security. There is no need for foreign presence".

In Syria, IS posted a video on YouTube appearing to show a Syrian man taking part in stoning his daughter to death for alleged adultery.

The Observatory said the execution took place in August or September in an IS-controlled rural area in the east of the central province of Hama.

Elsewhere in Syria, regime air raids killed at least 15 people Wednesday in rebel-held Nassib, on the Jordanian border, the Observatory said.

Meanwhile it was announced on Wednesday that the father of John Cantlie, a British hostage being held by Islamic State, had died.

Eighty-year-old Paul Cantlie passed away after "complications following pneumonia".

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