MURSITPINAR, Oct 16 (Reuters) - The advance of Islamic State fighters on Kobani stalled on Thursday according to a monitoring group, after U.S.-led coalition warplanes launched their heaviest bombardment yet on the militants, who have been assaulting the Syrian border town for nearly a month.
Last week Turkish and U.S. officials said Islamic State were on the verge of taking Kobani from its heavily outgunned Kurdish defenders, after seizing strategic points deep inside the town.
A dramatic ramping up of coalition air strikes reached a new crescendo in recent days, with Islamic State targets around Kobani being hit nearly 40 times in 48 hours. The barrage has halted the militants' advance, with Kurdish sources saying that Kurdish YPG fighters had managed to retake some territory.
The four-week assault has increasingly been seen as a key test of U.S. President Barack Obama's air strike strategy, and Kurdish leaders have repeatedly said the beleaguered town cannot survive without arms and ammunition reaching the defenders, something neighboring Turkey has so far refused to allow.
Islamic State has 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 Kobani would be a major setback for the Islamists and a boost for Obama.
Jet planes roared over Kobani on Thursday and gunfire echoed across the Turkish border from the town, as fighting steadily intensified through the morning, a Reuters witness said.
There were six air strikes overnight to the east of Kobani and clashes had continued throughout the night according to the UK based Syrian Observatory for Human Rights, who said neither side had made significant gains.
"Islamic State are trying to drive the YPG from the south to get more road access into the town," Rami Abdulrahman said by telephone.
"There were also clashes 6 km (4 miles) west of the city, by the radio tower," he added.
Sources within Kobani said Kurdish forces had pushed back Islamic State in southern and eastern parts of the town, which has been surrounded on three sides by the militants.
"We have seized back quite some territory yesterday," a Kurdish commander who gave her name as Dicle told Reuters early on Thursday.
"The clashes are still ongoing. We have seen many corpses of IS fighters yesterday, some had swords with them," she said.
A journalist in Kobani said that air strikes had allowed Kurdish forces to go on the offensive for the first time since Islamic State launched their assault four weeks ago.
"We walked past some (YPG) positions in the east yesterday that were held by IS only two days ago," Abdulrahman Gok told Reuters by telephone.
"Officials here say the air strikes are sufficient but ground action is needed to wipe out IS. YPG is perfectly capable of doing that but more weapons are needed."
Turkey has so far failed to bow to mounting pressure to aid Kobani, either by ordering in Turkish tanks and troops that line the border, or permitting weapons and ammunition to reach the town.
Ankara is reluctant to be sucked into the morass of the Syrian conflict without clear guarantees from western allies that more will be done to help repatriate 1.6 million people who have fled across the border from Syria.
Officials are also wary of arming Kobani's Kurdish defenders, who have strong links with the militant Kurdistan Workers' Party (PKK), which has staged a decades long insurgency against the Turkish government in the country's predominantly Kurdish southeast.
Turkish officials are increasingly frustrated with criticism of their actions towards Kobani, saying they have carried the humanitarian burden from the fighting, which saw 200,000 people cross the border from the Kobani area.
They also say air strikes fail to offer a comprehensive strategy against Islamic State, which has flourished in the power vacuum created by Syria's bitter war. Ankara blames Syrian President Bashar al-Assad for this, and wants him toppled from power, something western allies currently refuse to countenance.
Speaking on Wednesday, Turkish Prime Minister Ahmet Davutoglu said that Kurdish fighters who had fled into Turkey had been invited to return to Kobani to defend it, but had declined the offer.
He also spelled out details for so-called "secure zones" that Turkey wants to see set up in Syria close to its border, so that refugees can begin to return.
Zones should be created near the city of Aleppo, which has seen some of the fiercest fighting of recent months. Others would be set up near the Turkish border in Idlib province, Hassaka, Jarablous and Kobani, Davutoglu said during a television interview.
To boost legitimacy, the U.N. should enforce the zones, Davutoglu said, but failing that, the international coalition could provide the air cover needed.
"Turkey could provide all the help necessary if such protection zones are created. But when such protection zones do not exist, to ask Turkey to intervene on its own is to ask Turkey to shoulder this risk on its own."
Turkish officials are optimistic they can convince coalition partners to meet some of their demands, at which point Ankara would play a more active role, although it is unclear how long negotiations might take.
U.S. officials have said creating a safe zone is not a priority and NATO said last week it was not yet discussing such a move. (Additional reporting Seda Sezer and Dasha Afansieva in Istanbul and Oliver Holmes in Beirut; Writing by Jonny Hogg; Editing by Giles Elgood)