Parliament members voted on June 11 to oust al-Mashhadani, a Sunni, after a series of incidents in which he or his bodyguards physically attacked fellow lawmakers.
The Iraqi Accordance Front staged the boycott after al-Mashhadani was not asked to preside over today's session as they had requested, AP reported. The National Dialogue Front joined in the boycott.
Elsewhere in Iraq, the U.S. military said today that 11 of its soldiers were killed on June 23, AP reported.
The army said one of the soldiers died of a cause not related to combat. The army provided no further details and said the death is under investigation, according to the news agency.