BEIRUT (AP) — The al-Qaida-breakaway Islamic State of Iraq and the Levant has prevented food and medical supplies from reaching some neighborhoods in an eastern Syrian city and has ceased some of its operations in Syria while waiting for weapons to arrive from neighboring Iraq, activists said Friday.

The Britain-based Syrian Observatory for Human Rights said the siege is mostly on rebel-held neighborhoods of Deir el-Zour. It said an offensive by the Islamic State in eastern Syria against rival Islamic rebel factions has killed more than 640 people and uprooted at least 130,000 since the end of April.