Three US troops have been killed and another has sustained injury in the incidents occurring across Iraq, Press TV reported.
Two of the fatalities and the injury were caused on Saturday while the soldiers were "conducting operations in northern Iraq," AFP reported, citing a statement.
The agency quoted a US army spokesman, named Major Rob Phillips, as saying that two of the soldiers were killed in the northern city of Mosul.
Another American has died during an operation in central Iraq, read a US Military statement.
Earlier in the day, at least three US soldiers were wounded after two Iraqi troopers opened fire on them during a training session in a US military base in the south of Mosul, Reuters reported.
"Until now, we don't have any information on why the two Iraqi soldiers opened fire," said a senior police official after confirming the incident.
The American forces are expected clear out of Iraq by the end of this year as part of an agreement between Washington and Baghdad.
Iraqi Prime Minister Nouri al-Maliki has warned against any extension to the foreign presence on the strife-weary country's soil beyond what has been stipulated in Baghdad's agreement with Washington.