Iran has warned it will retaliate if attacked by the US, as reports from the US-based Human Rights Activists News Agency suggest the number of people killed in anti-government protests across Iran has risen dramatically to more than 500.

A meeting has been scheduled between the US and Iran, but the US has said it may act   in advance of that meeting if the need arrives. Speaking to Newstalk with more on this was Gregg Carlstrom, Middle East correspondent for The Economist.