A desperate search is under way for two missing brothers who were last spotted at a Bunnings.

They were last seen 10 days later shortly after 4.30pm on March 23 at Bunnings in Gungahlin, Canberra.

Oscar is described as 110cm tall with a slim build, short blonde hair and blue eyes.

Felix is 100cm tall, also with a slim build and short blonde hair with blue eyes.

Police believe the brothers are travelling with a man known to them in a white 2022 Toyota Hilux with the SA registration S393CTW.

He may have taken Oscar and Felix across the border into NSW, police said.

South Australia Police and the Australian Federal Police are working with state police to help track down the brothers.

Anyone who spots Oscar and Felix or has any information is urged to contact police on 131 444.