An Islamic State flag hangs amid electric wires over a street in Ain al-Hilweh Palestinian refugee camp, near the port-city of Sidon, southern Lebanon

World powers meeting on Syria have agreed to implement a nationwide ceasefire, US Secretary of State John Kerry has said.

But he said the ceasefire would not apply to the fight with jihadist groups Islamic State (IS) or al-Nusra Front.

He also said the powers had agreed to accelerate and expand the delivery of humanitarian aid.

The announcement comes as the Syrian army, backed by Russian air strikes, advances in Aleppo province.

A UN task force will be set up to ensure humanitarian access is granted to all sides, Mr Kerry said.