By Tom Perry and Seyhmus Cakan
BEIRUT Lebanon/DIYARBAKIR Turkey (Reuters) - A new offensive by al Qaeda offshoot the Islamic State on Kurdish-held areas of northern Syria has triggered a regional call for arms from the Kurds, and Turkish Kurds are coming to their aid.
The war in Syria has already drawn in an array of regional players and the regional Kurdish involvement complicates an increasingly fragmented scene across Syria and Iraq, where the Islamic state took control of large areas last month.
The hardline Sunni militants launched a new push towards the Syrian city of Ain al-Arab about two weeks ago using weaponry seized from Iraq including new missiles and U.S.-made armored Humvee vehicles, Syrian Kurdish officials say.
The predominantly Kurdish city is known as Kobani to the Kurds who have controlled it since 2012, part of an expansion of their influence following the collapse of central government control that has allowed for closer ties with Kurds across the border.
"Our brothers in northern Kurdistan - Turkish Kurdistan - have started a campaign to send youths to Kobani to defend it," said Redur Xelil, spokesman for the armed Syrian Kurdish group the YPG, or the People's Protection Units.
"There are some youths who have crossed the border from Turkey to Kobani who are now in the frontlines alongside the People's Protection Units," he said by telephone.
"It is all to repel the Islamic State."
A Turkish security official said Kurdish militants were heading to Syria from camps run by the Kurdistan Workers Party (PKK) in northern Iraq.
"The PKK sent some of its militants to Kobani after (Islamic State) attacks," the official, speaking on condition of anonymity, said.
Syria has already turned into a sectarian battleground with Shi'ite groups from Lebanon and Iraq fighting on the side of the Damascus government while Sunni foreign fighters from across the world are fighting with the Islamic State.
It is widely believed that Kurds from Turkey have been fighting covertly alongside the Kurds in Syria for some time. The Syrian Kurds have declared an autonomous provincial government in ethnic Kurdish areas.
Ain al-Arab and the surrounding areas fell under Kurdish control a year into the uprising against President Bashar al-Assad that has since turned into an armed insurgency dominated by radical Sunni Islamists.
ISLAMIC STATE "MAKES PROGRESS"
The Islamic State, which last month declared its leader caliph, or leader of all the world's Muslims, has seized no fewer than 10 villages near Kobani in the last 15 days, said Rami Abdurrahman, founder of the Syrian Observatory for Human Rights, which records developments in the Syrian war.
"They have certainly made progress," he said, adding that fatalities on both side were measured in the dozens.
A Twitter account affiliated with the Islamic State reported mortar attacks on Ain al-Arab on Saturday.
Ain al-Arab is the only part of a 300 km (190 mile) section of the border with Turkey not controlled by the Islamic State, previously known as the Islamic State in Iraq and the Levant (ISIL), Abdurrahman said.
Among the Kurds, he said the dead included two fighters from the PKK, a group based in the Qandil mountains in northern Iraq and which for years waged an armed campaign for Kurdish rights in Turkey. A ceasefire between the PKK and Turkey took hold last year.
The Union of Kurdistan Communities (KCK), the Kurdish militants' umbrella political group, on Saturday issued a statement calling on "all Kurds" to head to Kobani to "participate in the resistance and embrace it".
The attack on Kobani was "in fact an attack on the whole people of Kurdistan", it said.
Security sources in southeastern Turkey told Reuters that scores of Turkish Kurds had joined the Syrian Kurdish forces following the statement.
Abdurraham of the Syrian Observatory said 800 to 900 Kurdish fighters from Turkey were now fighting in Kobani.
One 21-year old Turkish Kurd in Diyarbakir, Turkey, who asked to be identified only by the initials A.B., told Reuters he was among Kurdish youths ready to go and join the Syrian Kurds.
"My Kurdish brothers are in a difficult position. I will go to Kobani, the KCK call is an order for us all. Every Kurdish youth should abide by this order. I know that many people went to Kobani from here,” he said.
(Additional reporting by Isabel Coles in Arbil and Ece Toksabay in Istanbul; writing by Tom Perry; editing by Philippa Fletcher)