Ayatollah Ali Sistani, one of Iraq's most senior Shia clerics, has called for the next government to dismantle militias operating in the country.
Ayatollah Sistani is a leading player in post-Saddam Iraq
The grand ayatollah said only the government should have weapons, and its forces should be loyal to the nation - not to individual political parties.
Many Iraqis blame militias for a sharp rise in violence after the bombing of a Shia mosque in Samarra two months ago.
On Thursday, at least seven people died after insurgent attacks around Baquba.
According to Iraqi army sources, 21 insurgents were killed and 46 were captured after the insurgents stormed police stations and checkpoints near Baquba, 55km (35 miles) north-east of Baghdad.
In Ramadi, meanwhile, an insurgent stronghold 115km (70 miles) west of Baghdad, US jets fired two missiles at insurgents during fighting, American army officers said.
Iraq's new PM-designate has vowed to take action against the armed groups.
However, Nouri Maliki has not said whether he intends to incorporate them in Iraq's security forces, or try to have them disbanded.
New cabinet approval
During a meeting in Najaf, the ayatollah told Mr Maliki he had to end bombings, drive-by shootings and kidnappings, fight corruption and restore electricity and clean drinking water.
Ayatollah Sistani also urged Mr Maliki to form a government of leaders who would put the national interest above "their personal, party or sectarian interests".
Ms Hashemi was head of the Iraqi Islamic Party women's affairs unit
The prime minister-designate has until late May to win parliamentary approval for a new cabinet, but has said he wants to move faster to create a grand coalition of majority Shia Muslims, Sunni Arabs and Kurds to combat the continued violence.
"The dialogue is still ongoing with the different parties from which the government will be formed. God willing, it will be settled next week," Mr Maliki said.
His comments come just hours after the assassination of a sister of the newly appointed Iraqi Vice-President, Tariq al-Hashemi.
Meysoun al-Hashemi and her bodyguard were gunned down in Baghdad, and is the latest in a string of high-level killings including one of Mr Hashemi's brothers on 13 April.
The BBC's Jim Muir in Baghdad says the attacks indicate that there is clearly a campaign against Sunni politicians trying to take part in the government.