As the ban came into effect on Wednesday, a raft of the world's most popular apps and websites face US$33 million in fines if they fail to purge Australia-based users younger than 16.

Other countries are considering less drastic ways to control teenagers' social media use. On Nov. 30, Singapore said it would ban the use of smartphones on secondary school…

Critics say new law is 'normalising surveillance' for young people and risks cutting them off from support networks.