Iraqi Prime Minister Nuri al-Maliki blamed "diabolical" and "treacherous" Arab countries for a protracted surge in nationwide violence in a speech on Sunday, but stopped short of naming individual countries.

The premier said suicide bombers were coming to Iraq from as far afield as Morocco, Libya and Yemen, but did not single out countries he described as "evil" which he said were supporting violent extremists in Iraq.

"Iraq is the target for some countries that are backing terrorism, and backing evil," Maliki said in a speech in the southern city of Nasiriyah.

"The world has united with us," he continued. "The (UN) Security Council, the European Union, and most Arab countries, except some diabolical treacherous countries."

The Iraqi leader warned countries that supported violence in Iraq would also suffer, arguing "this evil has started to expand, and it will reach those same countries, as it reached others previously."

Iraqi officials have alleged that Saudi Arabia and Qatar in particular have supported disaffected Sunni Arabs in western Iraq as they have staged anti-government protests in the past year.

More recently, Sunni-dominated western Iraq has erupted into a deadly standoff with security forces and their tribal allies facing off against anti-government militants and tribes.

A large section of Ramadi and all of Fallujah, both former insurgent bastions west of Baghdad, fell from government control late last month.

It was the first time anti-government fighters have exercised such open control in major cities since the height of the insurgency that followed the US-led invasion of 2003.

Fighting originally erupted in the Ramadi area on December 30, when security forces cleared a year-old Sunni Arab protest camp.

It spread to Fallujah, and militants moved in and seized the city and parts of Ramadi after security forces withdrew.

Diplomats including UN chief Ban Ki-moon have urged Iraqi authorities to pursue political reconciliation in a bid to end the standoff, and a months-long surge in nationwide violence, but Maliki has said the unrest is not due to domestic factors, and has blamed outside forces.