Iraq with two premiers?

Maliki was spurned by his own Shiite bloc on Monday in an apparent and internationally sought political breakthrough as Kurdish troops backed by US warplanes fought jihadists in Iraq's northwest.

President Fuad Masum told Abadi (pictured) - a former Maliki ally and parliament's deputy speaker - that the "country is in your hands."

A defiant Maliki gathered 30 loyalists and declared Abadi's nomination to be a "coup" against Iraq's constitution. Maliki vowed to take his case for a third prime ministerial term to Iraq's Supreme Court.

Earlier on Monday, Iraqi special forces said to be loyal to Maliki had deployed at strategic locations in Baghdad. Hundreds of Maliki supporters waved posters, shouting: "We are with you, al Maliki."

US warns Maliki

In Washington, President Barack Obama's administration warned its erstwhile ally Maliki "not to stir those waters" and welcomed Abadi's nomination as a "key milestone"

Later in the day in a televised address from his vacation location in Massachusetts, Obama called on Iraq to unite around an inclusive government and tackle "Islamic State" (IS) extremists who in the past two months have seized Mosul and swathes of northern Syria and northwestern Iraq.

Visiting Sydney, US Secretary of State John Kerry urged Maliki not to the disrupt the process of forming a new government.

Rebellion within Shiite bloc

Abadi, described as a more conciliatory figure, has 30 days to form a new Iraqi government.

Iraqi media said more than half of Maliki's State of Law bloc had joined the rebellion against the two-time Shiite premier.

Maliki was widely blamed for long alienating Iraq's Sunni minority - a trend exploited during the advance of "Islamic State" extremists.

Replacement welcomed internationally

Abadi's appointment by President Masum was also welcomed by UN chief Ban Ki-moon. He called on Abadi to "form a broad-based government acceptable to all components of Iraqi society.

EU foreign policy chief Catherine Ashton described Abadi's appointment as a "positive step" and urged him to form an inclusive government.

Standoff expected

President Hassan Rouhani of Shiite regional power Iran expressed fears that Iraq could fragment unless Maliki leaves power.

"It is important for Iran that a person approved by a majority of the representatives of the people in the Iraqi parliament takes power and begins his legal actions in Iraq." Rouhani reportedly told Turkey's president-elect RecepTayyip Erdogan in a phone call.

ipj/hc (dpa, Reuters, AFP)