President Barack Obama has said the deployment of 1,500 more US troops to Iraq marks a “new phase” against Islamic State militants.

He told CBS TV that the new troops, although non-combat advisers, could help Iraq go on the attack against IS.

A US-led coalition has been helping Iraqi and Kurdish ground forces with hundreds of air strikes since August.

Iraqi forces have now reportedly seized large parts of Baiji – home to Iraq’s biggest oil refinery – from IS.

Officials said troops now controlled some 50% of the town, about 200km (130 miles) north of the capital Baghdad.