Iraq's Sunni Muslim finance minister has said he holds Shia PM Nouri Maliki personally responsible for raids on his home and office by security forces.
Rafie al-Issawi, a prominent member of the al-Iraqiyya political bloc, said about 150 of his bodyguards and staff members had been arrested on Thursday.
He called it a "deliberate and premeditated act" by Mr Maliki.
On Friday, several of Mr Issawi's bodyguards were reported to have been accused of terrorism-related offences.
The raids occurred hours after President Jalal Talabani, a Kurd who has often mediated between Sunni and Shia politicians, was flown to Germany for treatment after suffering a stroke on Monday.
Foreign Minister Hoshyar Zebari told the Associated Press on Thursday that Mr Talabani was "starting to regain his senses".
At a news conference, Mr Issawi said "militia forces" had raided the finance ministry, his office and home in "an illegal action". "They arrested all the employees and guards," he said. "Is this the behaviour of a government, or the work of gangs?"
Mr Issawi accused the prime minister of being a man "who does not believe in partnership and does not respect the law and the constitution".
"Does Maliki want me to believe that he had no idea about this?" he asked. "This was a deliberate and premeditated act."
Mr Issawi, who is reported to have taken refuge in the residence of Parliament Speaker Osama al-Nujaifi, said the prime minister not returned his telephone call. He called for vote of no-confidence against Mr Maliki in parliament.
Mr Maliki insisted that he did not order the arrests, suggesting that they were the result of an investigation undertaken by the judiciary.
On Friday, Supreme Judicial Council spokesman Abdul Sattar Bayrkdar told the Associated Press that 10 of Mr Issawi's bodyguards were being held on suspicion of terrorism-related offences.
The head of the minister's protection force had been arrested on the strength of some suspects' "confessions" and had admitted taking part in terrorist attacks, Mr Bayrkdar added.
He did not give further details. According to the New York Times, the minister worked as a doctor in Falluja when Sunni insurgents fought US troops for control of the city in 2004.
The former US commander in Iraq, Gen Ray Odierno, later told Mr Maliki that he had looked into allegations that Mr Issawi was co-operating with the insurgents and found them to be baseless.
US officials were said to have been alarmed by Thursday's raids, and Ambassador Robert Beecroft has being trying to defuse the situation.
"We have been actively engaged with Iraqi political leaders on this matter," a state department official told the New York Times.
"We have urged the Iraqi government to uphold their commitments to due process and the rule of law as enshrined in their constitution."
Last December, several bodyguards of Sunni Vice-President Tariq al-Hashemi were arrested. Shortly afterwards, a warrant was also issued for Mr Hashemi, accusing him of running sectarian death squads.
Mr Hashemi denied the charges but fled to the semi-autonomous Kurdish region in northern Iraq before moving to Turkey. A court found him guilty in absentia and sentenced him to death in September.