BEIRUT (REUTERS) - Hundreds of families of Islamic State in Iraq and Syria (ISIS) militants and some injured fighters are expected to leave rebel-held areas of southern Damascus under a U.N.-brokered deal, a monitoring group said on Thursday.

Safe passage would be given from the Palestinian refugee camp of Yarmouk on the outskirts of Syrian capital and neighbouring Hajar al Aswad, said Rami Abdulraham, head of the British-based Syrian Observatory for Human Rights.

The families and some fighters will be taken to Raqqa in northern Syria, the stronghold of the militant Sunni Islamist group, and other ISIS-controlled areas over several months, eventually ending the group's presence near Damascus.

Islamic State has had a significant foothold in Hajar al Aswad, just a few kilometres from President Bashar al Assad's seat of power.

Syria's minister for national reconciliation, Ali Haidar, told Reuters that efforts were under way to get militants out of the Yarmouk camp but gave no details.

A UN spokesman told reporters in New York: "The UN is an observer to the agreement concerning Yarmouk, but not part of it, which we understand should come into effect in the coming few days."

Several local ceasefires and safe-passage agreements have been concluded elsewhere in Syria recently. One, brokered with support from Iran and Turkey, halted fighting in the town of Zabadani on the Lebanese border, and in two villages in northwestern Syria.

A deal was also reached in the last rebel-held district of the Syrian city of Homs that allowed rebels and their families to leave the besieged area. The UN said the agreement could help pave the way for a nationwide truce.