A search remains underway for two missing Aboriginal children who were last seen riding on their bikes in Adelaide’s south almost one week ago.

The two brothers, David aged nine and Peter,12, were last spotted about 5.15PM on Tuesday last week when they rode off on dark-coloured BMX bikes from their Christies Beach home.

Peter is described as 150cm tall with a slim build and black hair tied in a top knot. He was wearing a blue/white zip up jacket, long dark pants and white NBL sneakers.

Police say they have concerns for the children’s safety.

Family members have questioned why it took authorities five days to issue and alert.

Anyone who spots the or has any information is asked to contact the police assistance line immediately on 131 444.