Customs agents in Chile have detected low levels of radioactivity in cars shipped from the Japanese port of Yokohama.

Chile says the radioactivity was found in 21 of nearly 2,500 cars that arrived in Iquique aboard the Hyundai 106 cargo ship.

About a hundred port workers have protested, saying their health was at risk.

But Chilean deputy treasury secretary Miguel Angel Quesada said Monday that the Chilean nuclear commission has confirmed that the radioactivity is too low to cause damage to humans. He says the cars will be hosed down on board and any radioactivity will be contained inside inside the ship.

This is the first Japanese shipment to Chile to show radioactivity since Japan's massive earthquake and nuclear disaster.