The admission could further complicate relations between Washington and Turkey, which views the main Syrian Kurdish militia with suspicion because of its links to the Kurdish PKK insurgent group.

“There is direct coordination between Kurdish and American coalition forces,” Nawaf Khalil, spokesman for the Kurdish Democratic Union Party, told The Associated Press. “That's no secret. It began about a week ago,'' he said.

The party's armed wing, known as the People's Protection Units or YPG, has been struggling to defend the town also known as Ayn Arab against the ISIS despite dozens of U.S.-led airstrikes against the extremist group.

Khalil said Kurdish fighters provided “correct and credible intelligence” early on, building trust with the U.S.-led coalition. Therewas no immediate comment from U.S. military officials.

The battle for Kobani has emerged as a key test for the U.S.-led air campaign against the IS group in Syria, with the vast majority of strikes conducted in and around the embattled town.

Turkish armored vehicles patrol the border on October 17, 2014 near the Syrian town of Ain al-Arab, known as Kobane by the Kurds, near the southeastern village of Mursitpinar in Sanliurfa province.

Turkey has ground forces and tanks stationed just across the border but has declined to intervene. It views the YPG as an extension of the PKK, which waged a long and bloody insurgency in Turkey and is designated a terrorist group by the U.S. and NATO.

All armed Kurdish groups hope to one day create an independent nation state in the mountainous region of neighboring countries.

Khalil's acknowledgement of coordination came after State Department spokeswoman Jen Psaki said Thursday that U.S. officials had met with members of the Syrian Kurdish party for the first time.

Khalil said the meeting took place last week in Paris, and that it wasn't the first time the two sides had met. “The contact isn't new, but the admission of it is,” he said.

He said the party had not publicized the meetings because it did not want to cause more strife between Ankara and Washington.

But in Kobane fighting continued on Friday. Grey and black smoke covered the city and it was unclear what the source of the explosions were.US-led airstrikes have been targeting the area for two weeks.

The airstrikes appear to have had some effect to halt the group's onslaught on the town, which has been under assault since mid-September.

Capturing Kobani would give the group a direct link between its positions in the Syrian province of Aleppo and its stronghold of Raqqa, to the east.

ISIS militants mounted counterattacks overnight on posts taken by Kurdish fighters the day before in the Kobane amid intensified airstrikes by a US-led coalition, Kurdish activists said Friday.

The ISIS terrorists tried overnight to recapture the areas that our Kurdish fighters took in the eastern and southern fronts of Kobane, but they failed and they were pushed back," Farhad Shami, a Kurdish activist based in Kobane told DPA.

Idriss Nassan, the deputy head of Kobane's Foreign Relations Committee, said 15 to 20 per cent of Kobane was still in the hands of the terrorists group after it lost ground in the town.

Syrian Kurdish women stands outside tents in a refugee camp in the town of Suruc, Sanliurfa province, on October 17, 2014. Kurdish rebels have been infuriated by the lack of action by Turkey against ISIS terrorists trying to take the mainly Kurdish town of Kobane just across the Syrian border.