BEIRUT (REUTERS) - An attack by Islamic State in Iraq and Syria (ISIS) fighters on the Syrian town of Kobani and a nearby village has so far killed at least 146 civilians, the second-biggest massacre by the hardline group in the country, a conflict monitor said on Friday.

ISIS entered Kobani at the Turkish border on Thursday and clashes have continued with Kurdish YPG forces in the town, also known as Ayn al-Arab, said Rami Abdulrahman, head of the Britain-based Syrian Observatory for Human Rights.

Abdulrahman, who tracks the conflict using sources on the ground, said it was the biggest single massacre of civilians by ISIS since the killing of hundreds of members of the Sunni Muslim tribe Sheitaat tribe in eastern Syria last year.