Syria's most extremist group, the Islamic State of Iraq and the Levant (ISIL), has kidnapped nearly 200 Kurdish civilians from the Aleppo area, a monitor says.

"Fighters from ISIL on Thursday kidnapped at least 193 Kurdish civilians aged from 17 to 70 years from the village of Qabasin in Aleppo province," said the Syrian Observatory for Human Rights.

Observatory director Rami Abdel Rahman said the reasons behind their kidnapping were "unknown, but this kind of act takes place repeatedly in areas under ISIL control."

Rooted in al-Qaeda in Iraq, the Islamist militants first surfaced in the Syrian war in late spring last year.

Syria's Kurdish militias started fighting ISIL from very early on, as soon as the jihadists started pushing to take over resource-rich, Kurdish areas dotted around the country's north and northeast.

Rebels fighting to topple President Bashar al-Assad's regime initially welcomed the jihadists, but then turned against them because of their systematic abuses and quest for hegemony.

Al-Qaeda's official Syria branch - the Al-Nusra Front - has also turned against ISIL since.

ISIL is seeking to set up an Islamic state under its control along the Syrian border with Iraq.