He said that the illegal excavation had led to the degradation of the area.
Mr Oni warned that anyone found engaging in illegal mining would be held accountable and prosecuted.
The buildings were shut down during the sensitisation and enforcement campaign to commemorate the 2022 World Clean-up Day.
The government said indiscriminate disposal of refuse by traders was jeopardising its efforts to make Oyo one of Nigeria’s neatest states.
Oyo is endowed with granites, gold, gemstone, quarts, cassiterite, marble, garnet, tin-ore, moganite, niobium, agate, topaz, limestone, and tantalum.
