The Latest on the developments in Syria, where a Russia-U.S.-brokered cease-fire, now in its seventh day, is hanging in the balance after numerous violations (all times local):

11:35 a.m.

A senior Syrian opposition figure says the U.S.-Russia-brokered cease-fire that went into effect in Syria a week ago is now "clinically dead."

George Sabra of the High Negotiations Committee told The Associated Press on Monday that the truce has been repeatedly violated and did not succeed in opening roads for aid to enter besieged rebel-held areas.

Seven days after the cease-fire went into effect, aid convoys have not been able to reach besieged rebel-held neighborhoods of the northern city of Aleppo.

On Monday, the opposition reported 254 violations by government forces and their allies since the truce started on Sept. 12. Syrian state media said there were 32 violations by rebels on Sunday alone.

The Syrian army said in a statement last week that the truce will last until midnight Sunday.

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11:10 a.m.

Turkeys' president has announced a new push by Turkish forces and Syrian rebels aimed at capturing a town held by the Islamic State group.

Recep Tayyip Erdogan says the Syrian opposition forces, backed by Turkish troops and tanks, are determined to advance toward al-Bab to clear the region of terror threats.

The Turkish leader said on Monday that the offensive will last until the area "is no longer a threat" to Turkey.

Last month, Turkey for the first time sent tanks across the border into Syria to help rebels clear territory of IS militants and to contain the expansion of a Syrian Kurdish militia.

Erdogan's announcement comes as a fragile cease-fire, brokered by the United States and Russia and now in its seventh day, has mostly held despite numerous violations.