At least 300 Kurdish fighters crossed from Turkey into Syria overnight to battle ISIL trying to seize a strategic border town, a monitor said Saturday.

At least 300 Kurdish fighters crossed from Turkey into Syria overnight to battle ISIL trying to seize a strategic border town, a monitor said Saturday.

The Syrian opposing Observatory said the Kurds had joined the Syrian Kurdish People's Protection Units (YPG) in their fight against the ISIL as it seeks to capture the town of Ain al-Arab, known as Kobane to the Kurds.

The fighting around the strategic town has prompted a mass exodus into Turkey, which opened its border on Friday to fleeing Kurds and has since received 45,000 people, according to officials.

The clashes broke out on Tuesday evening, and the ISIL 'jihadists' have since seized 60 Kurdish villages in a lightening campaign.

The Observatory said fighting was continuing on Saturday, with heavy clashes in the vicinity of the town.