In the deadliest incidents in recent weeks, gunmen attacked a police station near the Baghdad International Airport and a car bomb exploded at the Hameed al-Najar Mosque.
In the Baghdad neighborhood of Amil, insurgents shot at the police station before they stormed the building, looting weapons, releasing detainees and killing at least 16 police officers.
U.S. military spokesperson Lt. Col. Jim Hutton said gunmen in 11 cars attacked the station with rocket-propelled grenades and small arms fire. Hutton said there were no American casualties, although a U.S. Humvee was damaged in the assault, and no word on the insurgents' casualties.
Police Capt. Mohammed al-Jumeili said several policemen and detainees at the station were wounded.
In a sign of continued instability in the capital, the U.S. Embassy Thursday barred employees from the highway leading to Baghdad's airport, which has been the scene of frequent attacks on vehicles.
Friday's second outbreak of violence occurred in the Baghdad neighborhood of Azamiyah, a predominantly Sunni area. A car bomb exploded at the Hameed al-Najar Mosque, killing 14 people and wounding 19.
No group has claimed responsibility for the bombing. Azamiyah was a major center of Sunni support for deposed dictator Saddam Hussein, and officials said the targeting of the mosque may be a bid by Sunnis to stoke civil strife in the area.
"Iraqi resistance has nothing to do with bombing mosques and churches and killing innocent people in markets and streets," said Sheik Ahmed Hassan al-Taha, imam of Abu Hanifa mosque. "These acts are against the law of God."
Insurgents have targeted police and security services in recent weeks. With Iraq elections less than two months away, security is a growing concern for the minority Sunnis, who have demanded a postponement.
Despite the continued attacks, President Bush on Thursday said the Jan. 30 vote should not be delayed.
"It's time for Iraqi citizens to go to the polls," Mr. Bush said.
As the election nears, the Pentagon is boosting the total number of American troops in Iraq from about 135,000 to 150,000 for the January elections.