The advance comes just days after Kurdish fighters loyal to the Democratic Union Party (PYD) expelled militants allied to the al-Nusra Front and the so-called Islamic State of Iraq and the Levant (ISIS) from the strategic Kurdish town of Ras al-Ain.

"Clashes raged during the night from Friday to Saturday, pitting (Kurdish fighters) against al-Nusra Front, ISIS and other (rebel) groups... near the villages of Tal Alu, Karhuk and Ali Agha," said the Britain-based Observatory.

The clashes "ended at 8:00 am (0500 GMT), when the Kurdish popular committees seized control of a... (key) checkpoint" there, said the group.

The Kurdish fighters then seized ammunition, light weapons, a vehicle mounting a heavy machine gun and a mortar launcher from the militants, the Observatory added.

PYD chief Salih Muslim has stated that Syria's Kurds are planning to create a temporary autonomous government to administer their regions in the north.

Kurdish regions have been administered by local Kurdish councils since President Bashar al-Assad's forces withdrew from the areas in mid-2012.

The redeployment was seen as a tactical move by the Syrian government, freeing up forces to battle militants elsewhere, and encouraging the Kurds to avoid allying with the opposition in order to maintain their new-found autonomy.

Since then, the Kurds have focused on maintaining security in Kurdish areas while strengthening control over their own affairs.

Kurds represent about 15 percent of the Syrian population.

Syria has been gripped by deadly unrest since 2011. According to the United Nations, more than 90,000 people have been killed and millions of others displaced due to the foreign-sponsored violence.

Damascus says the chaos is being orchestrated from outside the country, and there are reports that a very large number of the militants are foreign nationals.

HH/HH