A car bomb has killed at least six people, most of them pilgrims, in a mainly Shia town south of Baghdad, Iraqi police say.
Some Shia victims of Friday's mosque attack were buried in Najaf
The blast in Musayyib came as funerals were held in Baghdad for the 90 people killed when suicide bombers attacked an important Shia mosque in the city.
Tension has been high in Iraq since the bombing of a Shia shrine in February.
A senior government official has, for the first time, said Iraq is in a state of undeclared civil war.
"Iraq has actually been in an undeclared civil war for the past 12 months," Deputy Interior Minister Hussein Ali Kamal told the BBC's Arabic Service.
"On a daily basis Shia, Sunni, Kurds and Christians are being killed and the only undeclared thing is that a civil war has not been officially announced by the parties involved."
Mr Kamal added that while there was a civil war, it was "not on a wide scale".
Meanwhile, the Egyptian president has also said the violence amounts to a civil war, and warned the conflict threatened to spread beyond the country's borders.
The situation could deteriorate further if US troops withdrew, Hosni Mubarak said in an interview on satellite television station al-Arabiya.
Similar views to those of Mr Kamal were expressed in March by Iraq's former interim Prime Minister, Iyad Allawi. At the time, US President George W Bush said there were many voices that disagreed with that view.
As the bomb attacks on Shia communities continued, the leader of Iraq's largest Shia grouping issued a fresh plea for peaceful co-existence, and said the attacks were aimed at stopping efforts to form a government of national unity.
"Our people will not be drawn into the trap of civil war," Abdul Aziz Hakim told a gathering of his supporters in Baghdad.
Most of those who died in Musayyib were Shia pilgrims visiting a shrine, said senior police officers in the town.
Windows were shattered in a hospital nearly 800m (870 yards) away, witnesses said.
Saturday saw funerals in several Baghdad districts as relatives and friends of Shia Muslims killed in Friday's mosque attack buried the dead.
They chanted as they carried the coffins through the streets and beat their heads and chests in a traditional sign of grief and mourning.
Relatives also continued a search for loved ones in Baghdad's hospitals.
"These criminal acts are conducted by corrupt, terrorist groups that... have no sense of humanity," Jabar al-Maliki, an elderly cleric wearing traditional white robes, said at one funeral in Sadr City.
"We are the sons of one country, and one religion," he told the mourners.