In the latest attack in the southern city of Basra, a large blast shook a hotel killing at least four people, witnesses at the scene said.
There were at least two more wounded, including a child, hospital officials said.
The hotel is regularly used by British occupation forces, in charge of security for Iraq's second city, for press briefings.
Basra, a predominantly Shia city, has seen far fewer attacks than Baghdad and other areas surrounding the capital.
Earlier in the day attackers opened fire on a minibus carrying employees of a US-funded Iraqi television station northeast of Baghdad, killing three and wounding eight.
The officials said the employees of Diyala Television were being driven to work in the minibus east of the town of Baquba when guerrillas pulled up in a car and opened fire.
The blast came a day after a car bomb attack on a Baghdad hotel which US officials said killed around 17 people.
Security forces have been on alert for an expected increase in attacks ahead of the 20 March anniversary of the US-led invasion.
Basra has not seen the same level
of attacks as Baghdad
Fewer attacks in Basra
Also on Thursday, two US soldiers were killed and six others wounded near Baghdad as Iraqi rescuers completed the task of digging up the dead from a devastating car bomb.
A US marine was also killed while three others were wounded in western Iraq, according to military officials.
Baghdad hotel blast
The US army said Wednesday night's car bomb attack, which devastated the small Mount Lebanon hotel and neighbouring residential buildings, that it bore the hallmark of the Ansar al-Islam group or of Abu Musab al-Zarqawi, a Jordanian accused by Washington of working for al-Qaida.
Rescuers, some using their bare hands, worked into the early hours of Thursday trying to find people trapped under the smouldering ruins.
Locals helped carry away bodies torn apart by the blast. Twenty seven people were initially reported to have died in the explosion but US officials later revised the toll to 17 with 45 others injured.
However, the Iraqi Interior Minister said the blast killed six. "So far it looks like a car bomb. The number of casualties is six dead, one of them British and five of them Iraqi," Nuri Badran told reporters.
By first light, smoke was still rising from a smouldering house, its front wall ripped off in the explosion.
On the upper storey, a picture still hung on the wall, a mattress and carpet lying on the floor of what used to be somebody's bedroom.
The Bush administration is in full
attack mode against John Kerry
In another attack on Wednesday, the US army said, mortars fired on a US base near Baghdad killed one American soldier and wounded seven.
Bush campaign interrupted
The car bomb attack marred a White House campaign to stress the progress made in Iraq a year since the war began, ahead of the 20 March anniversary of the US-led invasion.
"We will meet this test with strength and resolve. Democracy is taking root in Iraq and there is no turning back," White House spokesman Scott McClellan said.
"This is a time of testing. We will continue to stay to finish the job for the Iraqi people."
Democratic presidential candidate John Kerry stepped up his criticism of President George Bush, charging that US troops were bogged down in Iraq with no end in sight.
Vice President Dick Cheney defended Bush and attacked Kerry in a speech in California.
"American leaders, above all the commander in chief, must be confident in our nation's cause, and unwavering until the danger to our people is fully and finally removed," he said.
US cable TV networks covered Cheney's speech but split their screens for live coverage of the carnage in Baghdad.
Mainly Iraqis killed
The Mount Lebanon hotel was mainly used by Iraqis and Arab businessmen. Rescue workers said most of the dead were Iraqis who were in neighbouring houses destroyed by the blast.
The US army said two British civilians were slightly wounded.
The blast gutted the hotel and
set buildings ablaze
The explosion set several buildings ablaze. With the second and third floors of the hotel still burning and spitting flames from the windows, residents tried to climb the stairs to rescue people stranded on upper floors. Some turned back, the heat too much and their eyes crying from smoke.
"I heard the explosion and ran down the street right away, but I could not get through the flames," said Ahmad Jassim, 23, who lives nearby. "I saw many people dead and there were people lying burning on the road, screaming."
Lebanese businessman Jihad Abi Muslih, who was watching television in a second-floor room in the Mount Lebanon when the bomb exploded, rushed out of the hotel, passing the manager who, covered in blood, groaned: "Oh God, help me please."
"The whole street was on fire when I went outside," Abi Muslih said. "The walls of the hotel were demolished."
The US military said the bomb was made up of 450kg of explosives and packed with artillery shells.