A "humanitarian pause" in attacks on rebel-held eastern Aleppo - part of a plan to allow civilians and fighters to leave - has come into effect, BBC News reveals.

The unilateral truce, announced by Russia, will last until at least 19:00 (16:00 GMT). Eight exit corridors have been designated from the east.

Russian and Syrian air strikes have been halted since Tuesday, October 18.

Rebels have rejected the plan and there are reports of clashes at one of the corridors out of the east.

Opposition sources say few civilians have yet been evacuated.

A correspondent in Aleppo for Orient News, a Dubai-based pro-opposition TV channel, said he and his crew had visited the two crossings intended for evacuation, but only a few civilians had left at the very start of the ceasefire.

Ammar Jaber accused Syrian government forces of targeting the corridors with sniper and rocket fire. He said "fierce clashes" were ongoing and 15 people had come under sniper fire.

Last month, Syrian government forces encircled the eastern section and launched an all-out assault backed by Russia.

Some 2,700 people have been killed or injured in the bombardment since then, according to the Syrian Observatory for Human Rights, a UK-based monitoring group. Some 250,000 civilians have been trapped by the fighting.

Western leaders have said Russian and Syrian air strikes on Aleppo could amount to war crimes, an accusation rejected by Russia.