Two American soldiers and an Iraqi interpreter were killed in a bomb blast south of Baghdad on Monday, US central command said on Tuesday.
Two further US soldiers were wounded in the attack.
The deaths followed another incident on Monday, in which one US soldier was killed and another wounded by a bomb attack west of Baghdad, according to Central Command.
Occupation forces have reported the deaths of 152 American service personnel in Iraq since 1 May when President Bush declared major combat was over.
Meanwhile, an employee of Iraq's main Shia political group has died after an explosion at the party's offices in the northern city of Kirkuk.
The worker was killed in the suspected resistance attack, targetting the Supreme Assembly for the Islamic Revolution in Iraq (SAIRI).
Mortar shells slammed into the party’s office, killing Khalil Karam Hasnawi, 29, and wounded a second person, said SAIRI’s chief Izz al-Din Musa in Kirkuk.
“The goal of these attacks is to wreck the future of Iraqis and disturb security,” he said in the oil-rich town, 255km north of Baghdad.
Musa claimed the attacks were carried out by al-Qaida. US occupying forces and Shia groups in Iraq regularly blame incidents on al-Qaida and Baathist elements.
SAIRI’s leader Ayat Allah Muhammad Bakr al-Hakim was killed in August along with about 83 civilians in a car bombing in Najaf.
SAIRI is represented on the US-appointed Iraqi Governing Council, a move which has angered both Sunnis and Shias in post-Saddam Hussein Iraq.