Iraqi Prime Minister Nuri al-Maliki's push for Saleh al-Mutlak, one of his deputies, to be removed from his post comes amid a political deadlock with the deputy prime minister's Sunni-backed Iraqiya bloc, which announced a day earlier that it was suspending its participation in parliament in protest at the premier's alleged centralisation of power.
The latest moves come with the US military having completed its withdrawal from Iraq on Sunday, nearly nine years after the 2003 invasion that ousted Saddam from power.
"The prime minister sent an official letter to parliament, asking it to withdraw its confidence in Saleh al-Mutlak after his recent statements," Ali Mussawi, media advisor to Maliki, told AFP.
Mutlak, who had been accused of being a supporter of Saddam's outlawed Baath party in the run-up to March 2010 elections that he was barred from standing in, told CNN on Tuesday that Washington was leaving Iraq "with a dictator".
And in a separate interview with his own Babiliyah satellite television channel, Mutlak charged: "Maliki is worse than Saddam Hussein, because the latter was a builder, but Maliki has done absolutely nothing."
Meanwhile, security officials said at least two guards of Vice President Tareq al-Hashemi, also a Sunni Arab and an Iraqiya member, were arrested in connection with a November 28 attack on parliament.
Local Iraqi news outlets also reported that an arrest warrant had been issued for Hashemi himself, but judicial and police officials declined to comment.
On Saturday, Iraqiya, which emerged as the largest bloc in March 2010 elections and has 82 lawmakers in the 325-seat parliament, issued a statement saying it was suspending its participation in parliament to protest what it said was Maliki's centralisation of decision-making.
Iraqiya, which garnered most of its support from Iraq's Sunni Arab minority, was out-manoeuvred for the premiership by Maliki, who, after finishing second in the elections, struck a deal with another grouping to broaden his power base.
The bloc, which controls nine ministerial posts, has not pulled out of Iraq's national unity government, however.
Iraqiya said the government's actions, which it claimed included stationing tanks and armoured vehicles outside the houses of its leaders in the heavily-fortified Green Zone, "drives people to want to rid themselves of the strong arm of central power as far as the constitution allows them to."