Australian Super Hornet jets have carried out air strikes in Iraq, killing an unspecified number of Islamic State (IS) fighters.

It was the second mission confirmed by Defence to have been carried out by Australian fighter jets.

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The first mission happened on October 6, with Chief of the Defence Force Mark Binskin confirming a pair of F/A-18F Super Hornets flew over Iraq without attacking any targets.

Meanwhile, two days of heavy air strikes by US warplanes have slowed the advance by IS militants against Kurdish forces defending the Syrian border town of Kobane.

Last week, Turkish and US officials said IS was on the verge of taking Kobane from its heavily outgunned Kurdish defenders, after seizing strategic points deep inside the town.

The tempo of coalition air strikes has increased dramatically, with US fighter and bomber planes carrying out 14 raids against IS targets near Kobane in the past 24 hours.

The strikes had seen the militants’ advance slow, but “the security situation on the ground in Kobane remains tenuous”, according to a statement by the US military’s Central Command.

One Kurdish commander told the BBC the IS militants had been driven out from many parts of Kobane, and that the town would soon be liberated.

Even so, heavy fighting continues there, clearly seen from across the border in Turkey.

The four-week Islamic State assault has been seen as a test of US president Barack Obama’s air strike strategy, and Kurdish leaders say the town cannot survive without arms and ammunition reaching the defenders, something neighbouring Turkey has so far refused to allow.

IS had been keen to take the town to consolidate its position in northern Syria after seizing large amounts of territory in that country and in Iraq.

A defeat in Kobane would be a major setback for the Islamists and a boost for Mr Obama.

Six air strikes hit eastern Kobane overnight and there was fierce fighting between Kurdish and Islamist fighters, but neither side made significant gains, according to the British-based Syrian Observatory for Human Rights.

Fighters from the Kurdish People’s Protection Units (YPG) later managed to seize a street in Kobane that had been held by militants, the Observatory said.

IS’s Kobane offensive is one of several it has conducted after a series of lightning advances since June, which have sent shockwaves through the region and sparked alarm in western capitals.

US officials have ruled out sending troops to tackle the group, but Kurdish forces have been identified as viable partners for the coalition, and Kurds in Iraq have received western arms shipments to bolster their cause.

No weapons or ammunition have reached Kobane however, fighters there say.

Kurdish forces killed at least 20 IS fighters west of Ras al-Ayn, another Syrian city on the border to the east of Kobane, the Observatory reported.

At least two YPG fighters were also killed during the clashes, in which Kurdish fighters seized Kalashnikovs, machine guns and other weaponry, the Observatory said.