Ljubicic said the driver's death was reported by the association of Croatian hauliers and the driver's employer.
Vjesnik daily says in Wednesday's issue that the driver who has allegedly been killed is Ivan Pavcevic of Komarnica near Nova Gradiska.
Ljubicic said the driver was from Nova Gradiska and was allegedly killed in the shelling of a US convoy near Tikrit. He added Washington had been contacted because the driver had worked for US troops.
Ljubicic said Zoran Sirocic was the driver who was arrested and imprisoned in Falluja allegedly after a fight with US marines.
Ljubicic underlined that both cases had to be checked and verified.
He regretted that Croatian citizens travelled to war-struck and other crisis areas despite the Foreign Ministry's warnings against it.
Countries on the ministry's high risk list included Iraq, Afghanistan, Algeria, Indonesia, Columbia, Pakistan, Saudi Arabia, Somalia, Sudan, Tajikistan, Uzbekistan and Venezuela.