"The explosion targeted a US patrol passing through the area," an Iraqi journalist in Mosul, Mahir al-Zanun, told Aljazeera on Friday.
Witnesses told al-Zanun a number of US soldiers from the targeted patrol were killed in the explosion, but a US military spokesman said the explosion did not leave American casualties.
Reporting from the scene, al-Zanun said US forces had sealed off the area to investigate the blast.
"The explosion also damaged nearby buildings and cars," he added.
Meanwhile, unrest continued across Iraq as armed fighters attacked two pipelines linking Iraq's southern oilfields to export storage tanks.
Oil exports from the southern terminals at Basra and Khor al-Amaya were running at about 1.5 million barrels (bpd) a day, compared to 1.6 million bpd on Thursday and 2.0 million earlier in the week.
Damage to oil infrastructure has
reduced vital exports
It was unclear whether the fall was due to the attack on Friday or to normal fluctuation in flow rates, shipping agents said.
Fighters on Thursday attacked eight pipelines linking a southern oilfield to a pumping station near Basra.
There were no indications that exports, which have proceeded sporadically this month, had resumed on Friday morning, but sources said they could restart at any moment to top off tanks.
In other developments, Khalil Khukhas, a member of the municipal council of Jaballa, west of Hilla, was murdered on Thursday evening by unknown assailants, informed sources told Aljazeera on Friday.
Also on Friday, two mortar bombs fell on the Turkmen Front headquarters in Kirkuk city but did not explode, Aljazeera reported.
The headquarters building was partially damaged, sources told Aljazeera. Iraqi police surrounded the building, preventing even the employees from entering it, the sources added.
Meanwhile, Iraqi police forces, backed by US troops, raided the Chinese House in al-Mansour area in Baghdad. The Chinese House is the headquarters of the Iraqi National Congress, led by Ahmad Chalabi.
The forces closed all roads leading to the headquarters before surrounding and raiding it.