Two Indigenous children have been refused permission to catch a bus without any money in Adelaide, sparking accusations of racial discrimination.

Adelaide resident, Mark Vorwerk, was catching the bus at the time and offered to pay the children’s fares but was told not to get involved by the bus driver.

Despite the fact that Adelaide's private bus operators are required to show "due care" to passengers unable to pay their fares, the driver refused both children.The South Australian Department of Planning, Transport and Infrastructure (DPTI), are currently looking into the incident.