Meanwhile, US chief administrator Paul Bremer has confirmed that Iraqi security forces now outnumber US-led occupation troops.
In the northern town of Mosul, a powerful suicide car bomb tore the front off a police station killing nine people and wounding 45, medics and police said.
"Nine people were killed, including two policemen and seven civilians," the head of the emergency room at the Mosul Hospital Najem Abdullah Shuaib said. Several Iraqi policemen were among the injured.
The blast occurred in the al-Thaqfa area of Mosul, 370km north of the capital Baghdad.
Witness Muhammad Abd al-Karim, 39, who works in the shop opposite the police station, told AFP that "an Opel sped up, got past the checkpoint and the driver blew up his car. There was an enormous explosion".
Elsewhere, three US soldiers were killed when their convoy was hit by a homemade bomb some 45km southwest of the oil centre of Kirkuk on Saturday morning, a US military spokesman said.
Their deaths pushed to 249 the number of US combat fatalities in Iraq since US President George Bush declared an end to major hostilities on 1 May 2003.
US Brigadier General Mark Kimmitt, deputy director of occupation operations in Iraq, said preparations were being made to tackle any surge in unrest around the Eid al-Adha holiday beginning Sunday.
An Iraqi policeman lies in a Mosul
hospital after the car bombing
Last October, a wave of carnage in Baghdad greeted the start of the Muslim fasting month of Ramadan, with attacks on the Red Cross and Iraqi police leaving 42 people dead and more than 200 wounded.
But, marking the graduation of almost 500 Iraqi police officers in Jordan, Bremer issued a statement Saturday stressing that more Iraqis than foreign occupation troops were responsible for law and order.
"Right now in Iraq, there are more Iraqis providing security than there are coalition forces here," he said.
The US-led occupation maintains about 140,000 forces in Iraq, while the combined strength of the Iraqi police, border guards, civil defence corps and protection service is 193,000.
However, many of those forces are still in the process of being trained by the US military.
Saturday's blasts came a day after three Iraqi soldiers were killed and a fourth seriously wounded in Mosul when unknown attackers opened fire on them at a military checkpoint.
The explosion served as another bloody reminder of Iraq's continuing resistance under the occupation.
Iraqi resistance to the occupation is proving to be stubborn and US-led occupation forces continue to face relentless attacks.
Despite the capture of Saddam Hussein, resistance attacks on occupation forces still average 18 a day.
Meanwhile, an Iraqi Turkman party official was shot dead on Saturday and another wounded by gunmen in the mostly Turkmen town of Taza, about 15km south of Kirkuk.