The report of the missing boys on Austrian state broadcaster ORF's Carinthian service was confirmed on Thursday to the Austrian Press Agency (APA) by Eva Moertl of the Youth Welfare agency.
On Thursday, a local search of the area was undertaken by police and fire service personnel.
The brothers should be currently in the custody of the Youth Welfare agency, as asylum seekers.
The pair have been living in Ferlach for about half a year. Moertl suspects that the two boys are on the run with their adult brother.
Austria has experienced significant overcrowding of accommodation for asylum seekers, who sometimes have to wait a very long time for their claims to be processed.