U.N. Secretary-General Ban Ki-moon urged countries to enforce an international arms embargo and economic sanctions on the Islamic State militant group in a bid to weaken the insurgency that has taken control of large swathes of territory in Iraq and Syria.
In a report to the U.N. Security Council on the world body's political mission in Iraq, obtained by Reuters on Tuesday, Ban described the rapidly deteriorating security situation fueled by the Sunni militants as "deeply worrisome."
IS was previously called the Islamic State in Iraq and Syria (ISIL or ISIS).
"I strongly condemn the upsurge of violence at the hands of ISIS and its supporters and call on (U.N.) member states, including Iraq's neighbors, to come together and support Iraq in its fight against terrorism," Ban wrote.
"Member states must meet their obligation to implement and enforce the targeted financial sanctions, arms embargo and travel ban imposed on ISIS," Ban said. "Terrorism must not be allowed to succeed in steering Iraq away from its path towards stability and democracy."
Al Qaeda in Iraq was blacklisted by the Security Council a decade ago and that designation was amended last year to include the Islamic State in Iraq and the Levant as alias. ISIL follows al Qaeda's hardline ideology, but alienated Osama bin Laden's successor Ayman al-Zawahri and others with its extreme violence.
The jihadi group, which claims authority over Muslims worldwide, has seized weapons from arms depots in Syria and Iraq, money from bank vaults in cities it has overrun, and controls other oil fields and farmlands.
It has declared an Islamic 'caliphate' on lands it has seized in both countries, and urged Muslims worldwide to flock there and wage holy war. The militants have been accused by rights groups of carrying out mass executions in Iraq.
Ban said reports of mass executions and other grave rights abuses by the Islamic State were "extremely disturbing."
Nickolay Mladenov, the United Nations special envoy to Iraq, said last month the advance of the militants in the country must be dealt with militarily, though success will hinge on a broad political consensus.
Ban said cross-border activities by ISIS had led to at least one major attack by Iraqi forces within Syrian territory when they targeted an ISIS supply convoy on April 27, while there were also reports that the Syrian air force had carried out attacks against militants in the border region on June 25.
"The international community, including countries in the region, must stand in solidarity with Iraq at this time of crisis," Ban said. "At the same time, Iraqi leaders must rise above narrow political or sectarian interest to confront the most serious challenges to the country in years."
Iraqi politicians named a moderate Sunni Islamist as speaker of parliament on Tuesday, a long-delayed first step toward a power-sharing government urgently needed to save the state from disintegration in the face of the Sunni uprising.