Two bombers have blown themselves up among crowds of Iraqis in the majority Shia town of Hilla, south of Baghdad, with the Polish military saying at least 30 people died and 50 were wounded.
Police said the first attacker, strapped with explosives, detonated his bomb among Iraqis waiting at a medical centre where police, army and civil service recruits had compulsory check-ups before being hired.
The second bomber blew himself up among a crowd of police commandos demanding higher wages. The Polish military controls the area around Hilla.
Fighters opposed to the presence of foreign troops in Iraq have increased attacks over the past month, killing more than 700 Iraqis since a new cabinet was announced on 28 April.
In February, a bomb in Hilla killed 125 Iraqis - the deadliest single attack since Saddam Hussein was toppled in March 2003.
Kurdish official killed
A senior Kurdish official died on Monday after being shot overnight by armed men in Kirkuk, a government official has reported.
Major General Ahmad al-Barazanchi, director of internal affairs of Kirkuk province and former police chief, died in hospital early on Monday after being shot multiple times late on Sunday, Ismail al-Hadithi, Kirkuk's deputy governor, said.
"Insurgents have targeted him to arouse sedition and sectarianism," al-Hadithi said. "He was walking without a bodyguard and in a sensitive area."
The killing is the second in several days, after Friday's slaying of a moderate Sunni Muslim tribal leader, Shaikh Sabhan Khalaf al-Jiburi, who had close ties to Iraqi Kurds in the northern city of Kirkuk.