"The secretary general urges the international community to unite in showing solidarity with Iraq as it confronts this serious security challenge," UN spokesman Stephane Dujarric said in a statement on Wednesday.

Ban demanded "full respect for international humanitarian law and human rights law in efforts to counter terrorism and violence in Iraq."

He noted that that "terrorism must not be allowed to succeed in undoing the path toward democracy in Iraq."

On Tuesday, the militants took control of Nineveh province and provincial capital Mosul, forcing “over 500,000 people in and around the city" to flee, according to Geneva-based International Organization for Migration.

Dujarric said more than 2,500 families have been displaced in Mosul, most of whom are staying in schools and mosques. He added that around 100,000 refugees have entered Arbil, the capital of Iraq's semi-autonomous Kurdistan region.

The situation intensifies "an already severe displacement crisis," said the UN spokesman, adding, "Resources are extremely limited."

Iraqi Prime Minister Nouri al-Maliki has said that the country’s security forces would confront the terrorists, calling the seizure of Mosul, Iraq’s second city, a “conspiracy".

SHI/SHI