Sources say hundreds of Iraq attacks planned
Web site posts apparent al-Zarqawi message to insurgents
U.S. forces do reconnaissance of Iraqi polling places.
Four suicide car bombings go off in 90-minute span.
Guard killed, 7 wounded in bombing outside political party office.
BAGHDAD, Iraq (CNN) -- Amid stepped-up attacks ahead of the January 30 elections, a top Iraqi police official Thursday said intelligence sources estimate 150 car bombs and 250 suicide attackers are prepared to strike in the coming days.
A top Iraqi police official told CNN Thursday the information came to light during interrogations of recently detained insurgents who said targets would include election centers and other locations, without being specific.
A U.S. military spokesman said of the information: "This is the trend we have been expecting as we get closer to the election."
The news comes a day after four suicide car bomb attacks in and around Baghdad killed at least 25 Iraqis and the bombers in just 90 minutes.
Several Islamic Web sites published claims of responsibility for all four bombings by the terrorist network led by Jordanian-born Abu Musab al-Zarqawi, who has ties to al Qaeda. (Full story)
Based on information from the Joint Coordination Center -- made up of coalition and Iraqi security forces -- at least three workshops producing car bombs and other explosive devices have been found in Baghdad in recent days, the police official said.
According to him, additional operations will be launched, including raids in search of bomb-making workshops.
Iraq remains under a state of emergency, which was renewed earlier this month by interim Prime Minister Ayad Allawi, who said "the terrorists continue to do everything they can to prevent the formation of a new government in Iraq."
The state of emergency essentially puts the country under martial law and allows Allawi to restrict freedom of movement, impose curfews and take security and military measures he deems necessary ahead of the January 30 elections.
Meanwhile, Chinese officials have appealed to Iraqi religious leaders to help win the release of eight Chinese migrant workers kidnapped by Iraqi insurgents. (Full story)
Beijing has sent officials to try to help win their release, Xinhua news agency has reported.
Kidnappers said China must clarify its intentions in Iraq within 48 hours, or the workers would be killed.
Also on Thursday the U.S. military said an insurgent attack Wednesday against a U.S. military convoy in the northern Iraqi city of Mosul ended with three dead, but no American casualties.
Insurgents were also unsuccessful in an attack on a civilian hospital in Mosul Thursday morning, the military said.
A military news release said soldiers from the U.S. Army's Stryker Brigade Combat Team were patrolling a road in northern Mosul Wednesday when they were fired on by gunmen in a moving vehicle. The soldiers returned fire, killing three insurgents, the military said.
No U.S. soldiers were wounded.
Iraqi Security Forces fought off an insurgent attack against the Al Salam Hospital in eastern Mosul Thursday morning, according to a U.S. military news release. No Iraqi soldiers or civilians were wounded, the military said.
Message: 'Fierce battle doesn't end quickly'
A voice claiming to be al-Zarqawi said in a recording found Thursday on an Islamic Web site that followers must be patient because "the fierce battle doesn't end quickly."
Although CNN cannot confirm its authenticity, the hourlong speech follows the style of al-Zarqawi's previous statements. The Web site hosting the audio is known to have been an outlet for his past messages.
The CIA is analyzing the recording to determine if the voice is al-Zarqawi's, and the results should be available by Friday, a U.S. official said.
Al-Zarqawi's group -- formerly know as Unification and Jihad but recently changed to al Qaeda in Iraq -- has been responsible for numerous car bombings, kidnappings and beheadings in Iraq.
The voice on the recording spoke extensively of the insurgency fight in the city of Falluja, calling it the "first pride of the Islamic nation."
In a U.S.-led offensive in the insurgency hotbed in November, the United States said 1,200 insurgents were killed, compared with 51 U.S. troops and eight Iraqi troops. But the voice thought to be al-Zarqawi's spoke as if the outcome of the battle remains undetermined.
He said the fight was carefully planned and he "intentionally lured the enemy into a street battle."
"Falluja should be our front battle," he said. "We should be patient and protect its defensive lines."
"This is now a street and city war with new tactics and defenses," he said.
The speech is filled with Quran verses and poetry, similar to the style used by al Qaeda leader Osama bin Laden, who -- in an audiotape the CIA said seemed authentic -- endorsed al-Zarqawi's terror campaign.
The United States has placed a $25 million bounty on both their heads.
In the recording, the speaker refers to al Qaeda's No. 2 man, Aywan al-Zawahiri, and former Afghan leader Mullah Omar as being in Afghanistan.
A U.S. official said U.S. intelligence has evidence al-Zawahiri is in the Afghan-Pakistan border area, but he declined to say if this suggests al-Zawahiri is in Afghanistan.
Other developmentsAn explosion near the entrance to a military base in British-controlled southern Iraq wounded five British soldiers and several Iraqi civilians Thursday afternoon, according to a British military spokesman. The blast happened at the Shaibah Logistic Base, about 12 miles southwest of Basra, the spokesman said. "It is not yet clear what caused this explosion nor is it clear if it was a suicide device," a spokesman said. British Prime Minister Tony Blair on Wednesday described pictures of Iraqis apparently being abused by British soldiers as "shocking and appalling." The pictures, released by prosecutors at the court-martial of three British soldiers, were discovered when laboratory technicians phoned police after a soldier took them to be developed. (Full story)Authorities will not disclose the locations of polling places in Falluja and other towns in Anbar province until shortly before the January 30 elections, said U.S. Marine Lt. Gen. John Sattler. Polling locations will be opened near most of the estimated half-million voting-age Iraqis living in the province. But officials do not want to give insurgents time to plan attacks against voters or polling places.
CNN's Cal Perry, Mohammad Tawfeeq, Octavia Nasr and David Ensor contributed to this report.