"The two main roads connecting Arbil and Dohuk to Mosul were cut off on Thursday with sand embankments as a precautionary measure after we detected an increase in deployments and movements of Iraqi forces near the front line with the peshmerga," he said.
The move came after Kurdish authorities said late yesterday they feared Iraqi government forces and allied paramilitary units were preparing to launch an assault on the autonomous northern region.
The warning came amid spiralling tensions between Iraq's Kurds and central authorities in the wake of last month's Kurdish independence referendum.
In the oil-rich region of Kirkuk, which is disputed between the Kurds and Baghdad, a local commander told AFP there were no immediate signs of movement.
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"We have seen no unacceptable movement on the part of Iraqi forces," Wasta Rasul, the commander of peshmerga forces in southern Kirkuk, told AFP.
The coalition has worked with the peshmerga, as well as Iraqi pro-government forces, in the battle to oust IS from areas it seized in Iraq in mid-2014.
Security sources said that Iraq's elite Counter Terrorism Service (CTS) and Rapid Response Force had deployed more forces near Rashad, a village some 65 kilometres south of Kirkuk, near peshmerga positions.
Asked by AFP, the spokesman for Iraq's Joint Operations Command, refused to confirm or deny any preparations for an offensive.
Iraqi forces last week retook control of Hawija, one of IS's last enclaves in the country, which is close to Kurdish majority areas.
Baghdad and Arbil have been locked in a stand-off since voters in Kurdistan overwhelmingly opted two weeks ago for independence in a referendum that the central government slammed as illegal.
Iraq has cut Kurdistan off from the outside world by severing air links to the region, while neighbouring Turkey and Iran have threatened to close their borders and block oil exports.