In a recent statement, the prime minister dismissed the rhetoric as political posturing ahead of provincial elections scheduled for April and warned his opponents not to forget the dark days of sectarian fighting "when we used to collect bodies and chopped heads from the streets."
Al-Maliki's spokesman, Ali al-Moussawi, criticized al-Issawi's participation in the protest Wednesday.
"He can't be in the government and use the street against it at the same time. If he can't shoulder his responsibilities then he has to step down so that another person can take over," he said.
The political tensions are rising at a sensitive time. Iraq's ailing President Jalal Talabani is incapacitated following a serious stroke last week and is being treated in a German hospital. The 79-year-old president, an ethnic Kurd, is widely seen as a unifying figure with the clout to mediate among the country's ethnic and sectarian groups.
Also Wednesday, the United Nations mission to Iraq said its monitors have determined that a hospital that treated a member of an Iranian exile group who died this week at a refugee camp near Baghdad did not consider his health condition serious enough to warrant hospitalization when he arrived for treatment in November.
An organization representing the Mujahedeen-e-Khalq exile group on Monday accused Iraqi authorities of preventing 56-year-old Behrooz Rahimian from being hospitalized, and alleged that the U.N. failed to take sufficient steps to intervene. Iraq considers the MEK a terrorist group and wants its members out of the country.
The U.N. mission in Baghdad said in a statement Wednesday that it "does not have any indication so far that treatment was obstructed by the Iraqi authorities." It noted that representatives for the refugee residents told U.N. monitors that Rahimian "appeared to be in good condition until the time of his death."
Schreck reported from Baghdad. Associated Press writer Sinan Salaheddin contributed.
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