After the Supreme Court ordered suspension of mining operations in the district, the administration has seized 49 trucks illegally transporting iron ore at Alighar on the city outskirts.
Police said the value of the material seized on Saturday was being ascertained.
The district collector said the vehicles apparently belong to Bellary Mining Corporation.
He said the truck drivers claimed to have obtained the permit for taking out the iron ore on July 30, "which is against the Supreme Court order which came on July 29 and so no permit can be issued".
The apex court had ordered immediate suspension of mining and transportation of iron ore from Bellary district, saying "over-exploitation" of the area has caused large-scale environmental degradation.