A group led by Abu Musab al-Zarqawi, the 38-year-old Jordanian said to be the mastermind behind a string of spectacular suicide bombings in Iraq, has claimed responsibility for the executions.
The Egyptian, identified as Ibrahim Mohammed Ismail, 39, an employee of a Kuwaiti firm which supplies water to US forces in Iraq, was shot thrice as he knelt on a busy street corner by a masked man, as people and traffic passed by.
Ismail had earlier identified himself and made a fervent appeal to foreign drivers to stay away from Iraq before he was led away blindfolded and handcuffed for his public execution.
"Despite all the warnings from the mujahideen ... these apostates continue to help the occupier shed the blood of those who refuse to submit," the executioners said.
In another video posted on an Islamist web site, two Shia drivers were beheaded on a pavement in daylight, as a crowd looked on.
"We advise those working for the Americans to stop doing so. Don't come to Ramadi, the city of the Mujahideen, otherwise you will be killed," the two drivers said earlier while admitting they worked at a US base in Iraq.
Their severed heads were held aloft by the killers amidst shouts of "Allahu Akbar", or "God is greatest".
"Anyone who helps the occupying enemy in any way" would meet the same fate, the killers warned.
Al-Zarqawi also released an audiotape Sunday urging an all-out war on the January 30 elections, which are likely to be dominated by Iraq's Shia majority.
Zarqawi declares war on Iraq election
The elections were a "wicked trap aimed at putting the Rafidha (a derogatory term for Shias) in the seat of power. Four million Rafidhi have been brought in from Iran to take part in the elections so that they realize their aim of taking most seats in the pagan assembly," he said.
