* Battle in border town on refugee escape route to Turkey
* Syrian rebels fear Kurdish autonomy
* Battle may have been pre-emptive strike on PKK
Seven al Qaeda-affiliated rebels were killed in a battle with a Syrian Kurdish militia on Wednesday, as violence between Syria's Arabs and Kurds increased, opposition activists said.
The fighting in Atma, a town on the Turkish border which is a main escape route for refugees fleeing the civil war, shows how the region has become a battleground for a myriad of armed groups in a scramble to grab territory, opposition sources said.
As well as the seven members of the the al-Qaeda linked Islamic State of Iraq and the Levant killed in fighting with the PYD, the Syrian arm of the Kurdistan Workers Party (PKK), two women PKK recruits were also killed by mortar fire on the outskirts of the nearby town of Jandaris, the sources said.
Since the start of the revolt, President Bashar al-Assad's forces have pulled out of Kurdish regions, including Ifrin, where Atma is located, handing de facto control to the PKK.
While fear is widespread among Kurds of a possible Islamist takeover if Assad falls, the PKK has come under criticism from other Kurdish groups for having ties with Assad's forces and has also been accused of killing peaceful Kurdish activists, charges the group denies.
Opposition activist Mohammad Abdallah said officers from Assad's army visited PKK leaders in Jandaris in the last week to discuss military cooperation, prompting the rebels to launch a pre-emptive strike.
"There is a feeling that the Kurds were fortifying Jandaris as part of a plan to carve a Kurdish zone in Ifrin with the help of the regime," Abdallah said. "Fighting has been heavy all day, and rebels have brought heavier guns to defend Atma and to target the PKK."
Another activist in the town said the PKK had taken positions in high ground around Atma. "Most of Atma is now within site of PKK snipers. Clashes with rocket-propelled grenades are taking place on the hills," he said.
Kurds comprise around 10 percent of Syria's 21 million population. They are concentrated in Ifrin and other areas of the northwest, in parts of Damascus and in the northeastern oil producing area of Qamishli, where there has also been intense fighting between Kurds and rebel units and Arab tribes opposed to de facto Kurdish autonomy.
Seeking to mend ties with the Kurdish community, Syrian opposition leaders in exile attempted, at a meeting in Istanbul this month, to expand the Syrian National Coalition to include members of the Kurdish National Council, a grouping of the main Kurdish parties that does not include the PYD.
But the effort was put off as the coalition debated at length a joint declaration with the Kurdish Council that defines the Kurds as a separate people in a united Syria.