Iraqi President Jalal Talabani has called on Iraqis to help stop sectarian violence after figures showed it killed 1,091 people in Baghdad last month.
April's murder rate reached more than 30 a day
Mr Talabani said he was "shocked and angry" at daily reports of murders.
He was speaking as PM-designate Nouri Maliki prepared to name his government, which analysts hope will be better able to tackle the growing violence.
Sectarian violence, sparked by the bombing of a Shia shrine in Samarra in February, has swept across Iraq.
Bodies, some of which have shown signs of torture, have been discovered on a daily basis in the capital. The latest reports said 13 bodies were found on Wednesday.
Sunni Muslims say government-backed Shia militias are behind many attacks, a charge the Iraqi government denies.
'Quell this bleeding'
Mr Talabani said in a statement issued by his office he was shocked to hear reports of "people killed on the basis of their identity".
Mr Talabani cited a report from a Baghdad morgue saying 1,091 people were killed between 1 and 30 April.
He said that the number of dead around the country reflected "a situation no less dangerous than the results of terrorist acts".
Behind every unidentified corpse is "an orphan, a starving father or a grieving wife," he said.
He said that the rapid formation of a national unity government might help, but called for swift action.
"I urge all political parties and security forces to quickly move to quell this bleeding from crimes aimed to create doubts between sons of Iraq and disrupt national unity," he said.
Earlier on Wednesday, at least 11 people were killed when gunmen ambushed a bus outside Baquba, north of Baghdad.
The victims were reportedly employees of a state-run electricity company travelling to work.
The gunmen ambushed the bus and "sprayed it with bullets, killing 11 people", a police officer was quoted by the AFP news agency as saying.
When police arrived at the scene to investigate "the bus exploded", the police officer added.
A day earlier, at least 24 people were killed in a car bomb blast in the northern town of Talafar.
On Tuesday, Mr Maliki said he had nearly completed the task of forming a new government of national unity.
He said he hoped to form a new administration within two days. Under the constitution, he has until 22 May to finish the task. His cabinet list has to go before the Iraqi parliament for approval.
A senior negotiating source told Reuters news agency that most of the work was done but the government was unlikely to be ready on Wednesday.
"We still need a few days," the source said.
The US envoy, Zalmay Khalilzad, told a conference in Jordan on Tuesday that Iraq was "strategically heading in the right direction now".
"The formation of a government of national unity will set the stage for efforts to diminish violence," he said.
"There can be no legitimate armed opposition once a permanent government in which Sunni Arab leaders have a vital role is in place," he said.
Meanwhile, Paris-based media watchdog Reporters Without Borders has urged Mr Maliki to investigate the upsurge in killings of Iraqi journalists. Five Iraqi journalists and media assistants have been killed this month.
The BBC's Sebastian Usher says Iraqi journalists have come under increasing attack in the last 18 months, partly because they are the most visible reporters in the country now that Western journalists are mostly confined to Baghdad.