Iraqi forces have discovered a chemical warfare agent in Mosul alongside a cache of Russian surface-to-surface missiles.

Fighters from the so-called 'Islamic State' group have killed some 70 civilians in Mosul this week over accusations of collaboration with Iraqi forces pushing into the city to drive them out, the United Nations has said.

Iraqi special forces have entered the outskirts of Mosul, taking the state television building and advancing despite fierce resistance by Islamic State (IS) fighters who hold the city.

Iraqi special forces have moved more than 1,000 people from villages near the front lines of the battle to retake the city of Mosul from Islamic State.