Tenuous, fragile, dire.

These are the words being used by official to describe the military situation on the ground from Syria to Iraq where both Kurdish militia and the Iraqi army are struggling to halt the advance of jihadist fighters from the Islamic State (IS) group.

Most of the world's attention has been focused on the beleaguered Syrian border town of Kobani. Yesterday, fierce fighting there concentrated on southern and eastern neighbourhoods in an area known as the "security quarter" where municipality and other local government offices are located. Tall plumes of smoke could be seen rising from the district and the sound of gunfire was close to constant as battles raged into yesterday afternoon

Despite airstrikes by the US-led coalition, Kurdish militia dug in around the city found themselves under renewed onslaught from IS fighters who appeared to have been resupplied over the last few days. A Kurdish military official, speaking from Kobani, said IS had brought extra tanks and artillery to the frontlines, while street-to-street fighting was making it harder for the warplanes to target IS positions.

"We have a problem, which is the war between houses," said Esmat Al-Sheikh, head of the Kobani defence council. "The airstrikes are benefiting us, but IS is bringing tanks and artillery from the east. We didn't see them with tanks, but yesterday we saw T-57 tanks," he added.

While IS has been able to reinforce its fighters, the Kurds have not. The IS siege has left the Kurds with only one supply route at the Turkish border to the north.

"The city is in danger," admitted Farhad Shami, another Kurdish activist in Kobani, while one of this colleagues, Ismet Sheikh Hasan, went as far as to say the situation inside the city was "dire".

The director of the Britain-based Syrian Observatory for Human Rights, Rami Abdurrahman, added that the town's Kurdish militia are putting up a fierce fight but are outgunned by the jihadists.

Since IS launched their assault on Kobani in mid-September, at least 500 people have been killed and more than 200,000 have been forced to flee across the border into Turkey.

In perhaps the most alarming statement to date, an estimated 12,000 or so civilians still in, or near, Kobani are likely to be "massacred" by advancing IS extremists, a UN official warned yesterday.

"You remember Srebrenica? We do. We never forgot. And probably we never forgave ourselves for that," said Staffan de Mistura, the UN Syria envoy, invoking memories of the 1995 slaughter of thousands of Muslims by Bosnian Serb forces.

The civilians of Kobani "will be most likely massacred", said the Italian-Swedish diplomat, who was appointed to the UN post in July. "When there is an imminent threat to civilians, we cannot, we should not be silent."

But it not just in Syria that the IS advance is threatening towns and cities. Iraq's army is under mounting pressure in the country's vast Anbar province. So desperate is the situation there that, according to local TV channel al-Sharqiya, the region's provincial council has written to Iraqi central government and requested US ground troops to aid the fight against IS.

The vice-president of Anbar's provincial council, Faleh al-Issawi, has warned the province could "fall in 10 days" to IS.

"It's tenuous there. They are being resupplied and they're holding their own, but it's tough and challenging," said a senior US defence official of the Iraqi forces, who spoke on condition of anonymity. "I think it's fragile there now."

So far, however, IS have failed to take the strategic Haditha dam, Iraq's second largest, with coalition bombing raids helping the Iraqi government fend off the jihadist assaults.

Despite this, US officials admit the situation has glaringly revealed how Iraqi troops are far from an effective fighting force and in urgent need of further training.

The same officials point out that the difficult circumstances in Anbar contrast significantly from battlefield reports in the north of Iraq, where Kurdish soldiers are said to have made some headway against IS.

"There's no comparison" between the ability of the Kurdish forces and the Iraqi government army, one US official insisted.

"The Kurds are moving, they're taking back towns and territory, and were able to co-ordinate with coalition forces," he said.

By contrast, the Iraqi army has launched a number of offensives in the country's west that have quickly fizzled out.

"They start an operation and it stops after a kilometre," said the official, who spoke to news agencies on condition of anonymity.

Should IS take control of Anbar it would give their forces a clear route into the Iraqi capital.

"If IS controls Anbar, they would be able to threaten serious targets in Baghdad," Saeed al-Jayashi, an Iraqi security expert, confirmed last week. The government would lose the Haditha dam, and the security forces would have to retreat," he said. "There would be a bloodbath."

His views were echoed by other analysts. "They're so close to Baghdad now," said Sajad Jayid, Research Fellow at the Iraqi Institute for Economic Reform. I mean, they have always been around but they are now literally 20 minutes drive."

This ever-growing threat to Baghdad was again brought home yesterday when a suicide bomber detonated his explosives belt in a market north of the capital, killing 11 people and wounding 21 others. The attack took place in an area that has been the scene of clashes between Iraqi forces and IS fighters. In other violence, four Iraqi soldiers died in a friendly-fire incident in the town of Udaim, 53 miles northeast of Baghdad.

The soldiers, who had been wounded by IS fighters, were being taken to hospital when Shi'ite militia volunteers who mistook them for IS fighters fired a rocket-propelled grenade at their vehicle.

For the time, however, it is the plight of the Syrian town of Kobani and its Kurdish defenders and civilians that continues to make headlines, causing considerable humanitarian and political concern.

Not only would the symbolism of US-led airstrikes failing to stop IS from overrunning Kobani provide an early setback to US President Barack Obama's three-week old Syria air campaign, but it would free up thousands of IS jihadist fighters to pursue territorial gains elsewhere in Syria and Iraq.

"Judging the overall coalition from a single town in northern Syria ... is slightly unfair," points out Shashank Joshi of London's Royal United Services Institute. "But I think it will dent overall confidence in the coalition and it will concern many people as to whether the US can really stop this movement."