VATICAN CITY (AFP) - Pope Francis called on Wednesday for concrete help for millions of refugee families around the world and sent his prayers to those forced to flee an insurgency spearheaded by Islamist militants in Iraq.

"The number of brother refugees grows and, over the past few days, thousands of others have been forced to abandon their homes to save their lives," he told the crowds in St Peter's Square during the weekly general audience.

"Millions of refugee families in many countries and of all religious faiths are suffering tragedies and wounds which will be cured with difficulty," he said.

"Let us be close to them, sharing their fears and uncertainties for the future, and easing their suffering in a concrete manner."

In Iraq, a lightning assault by the jihadist Islamic State of Iraq and the Levant (ISIL) - whose fighters have captured a large area of territory stretching towards the capital Baghdad - has displaced hundreds of thousands of people.

In neighbouring Syria, a three-year civil war has killed more than 162,000 people and forced nearly half the population to flee their homes.