The latest bomb exploded outside city council offices in Yathrib, which lies north of Baghdad, an occupation spokesman said on Thursday.
Four Iraqis were wounded.
Earlier, at least 35 people were killed and more than 100 others injured in a car bomb of the Civil Defence Corp recruitment centre in Baghdad, said the Iraqi Health Ministry.
Bodies, bloody and battered, lay tangled in the street outside
the centre, as ambulances on the scene struggled to deal with the chaos.
"The explosion took place near al-Muthana airport at the entrance to a US military base. Members of the former Iraqi army were gathering to receive their salaries," said a policeman.
The casualty toll at three local hospitals kept rising as ambulances and police trucks brought in the casualties, many of them badly mutilated by the force of the blast.
The toll is expected to rise as the Alawi al-Hilla neighbourhood was crowded at the time of the explosion. Numerous bus and taxi stations are based there.
The toll from the Baghdad blast
is expected to rise
The huge explosion echoed over central Baghdad and a plume of smoke rose near the sprawling compound housing the US-led administration's headquarters.
The military had no immediate information on the blast, but a spokesman said they were checking.
First Hungarian death
The Hungarian contingent in Iraq lost its first soldier in an explosion on Thursday morning in al-Suwayrah, southeast of Baghdad, Defence Minister Ferenc Juhasz said in Budapest.
"Today a 47-member convoy departed from the Hungarian base of Hilla towards a Ukranian base when it came under attack," Juhasz said. A 27-year-old soldier died in the attack.
"An explosive device went off just next to the Hungarian convoy," he added.
Just an hour earlier, a US soldier died of wounds sustained during a rocket attack on an occupation force base in Iraq as Baghdad comes under intense attack.
Three soldiers have now died as a result of the Wednesday attack north of Baghdad.
Violence has surged since Iraq's
interim government was appointed
One died immediately at the scene of the attack, the other two in a field hospital.
The attack targeted the Anaconda base near Balad and
wounded 23 others - including at least 12 soldiers.
Numerous bomb attacks have continued to be launched in the Iraqi capital.
Shortly after midnight, exploding mortars were lobbed at the US headquarters in the capital.
The explosions set off sirens at Saddam Hussein's former main palace in the heavily fortified US-led occupation headquarters.
However, a military statement said there were "no injuries to personnel or damage to equipment" caused by the midnight attack in central Baghdad.
Locals say the attack took place at around 00:45 am on Thursday.
Four Iraqis were killed and 25 injured on Thursday in clashes between supporters of Shia leader Muqtada al-Sadr and the US occupation troops in the Baghdad suburb of al-Sadr city.
The dead included two children and a fighter from al-Sadr's Mahdi Army, Aljazeera's correspondent in Baghdad reported, quoting hospital sources and al-Sadr's office.
The clashes erupted when a US patrol entered al-Sadr city. Two US military vehicles were damaged in the fighting.