What is Iran's role in Iraqi fight against IS?

The Iraqi prime minister, Haider Al Abadi, is in Tehran for talks with Iran's Supreme leader, Ayatollah Ali Khamenei, about the fight against Islamic State militants.

Iran is playing a key role in that battle, through political and military support of Shia militias and its advisors on the battlefield.

But, there are concerns about their role, and the growing influence of Tehran.

Orla Guerin reports.