US warns Syria on using chemical weapons

President Barack Obama has warned Syria's President Bashar al-Assad that his government will be held accountable if it uses chemical weapons.

Obama was speaking after Damascus said chemical weapons would not be deployed inside Syria but against foreign attack.

UN Secretary General Ban Ki-moon said any thought of using chemical weapons would be reprehensible.

Fierce fighting has taken place in Aleppo, where rebels claim to have captured parts of the city.