Iraq's interior minister has admitted death squads and other unauthorised armed groups have been carrying out sectarian killings in the country.
But in a BBC interview, Bayan Jabr denied allegations that these groups were linked to his ministry.
Mr Jabr blamed the proliferation of civilian security companies and licensed protection agencies used by other government ministries.
Sunni Muslims say government-backed Shia militias are behind many attacks.
The BBC's Andrew North in Baghdad says that every day more victims of Iraq's sectarian strife turn up. Corpses bound and shot are dumped at the roadside.
The US military says more than 1,300 civilians were victims of sectarian violence last month alone.
Some analysts believe the real figure is much higher, as many bodies are never found.
'Out of order'
In his interview with the BBC, Mr Jabr said despite appearances, those involved in recent attacks were not genuine police officers.
"Terrorists or someone who support the terrorists... are using the clothes of the police or the military," he said.
"Now you can go to the shop and buy it."
He said problems also stemmed from the existence of non-governmental security agencies like the Facility Protection Service, an armed force set up during the US-led administration of Iraq in 2003 to guard official buildings.
Mr Jabr called the 150,000-strong FPS "out of order, not under our control". He also implicated the involvement of about 30,000 civilian security guards operating in Iraq.
Sectarian tensions have been high since the bombing of a Shia shrine in Samarra in February.
In the latest violence on the ground:
- A suicide car bomber strikes in the northern city of Talafar, killing two shoppers at a vegetable market
- Three civilians die in a roadside bombing in Baghdad
- Three government employees are gunned down in different attacks in the capital
- A car bomb explodes in Khalis, north of Baghdad, killing two
- Two US soldiers die in a roadside bomb, with a third reported killed in Baghdad.
A delay in reaching agreement on a new government is thought to be partly responsible for fuelling the violence.
Parliament is due to convene next Monday - for only the second time since elections four months ago.
"There are signs that there will be agreement on all problems concerning formation of the government," the speaker, Adnan Pachachi, told reporters.
Arab foreign ministers are due to meet in Cairo on Wednesday to discuss the violence in Iraq. The Baghdad government is not taking part.
Last week Egypt's Hosni Mubarak suggested that a civil war was imminent in Iraq.
Prime Minister Ibrahim Jaafari - who has the support of the Shia bloc - on Sunday dismissed the claim.