Instagram owner Meta and other social media firms said on Tuesday they will comply with a ban on users under the age of 16, adding that they will start deactivating accounts once the law takes effect on December 10.

At a parliamentary hearing, Meta, ByteDance (the owner of TikTok), and Snap (the owner of Snapchat) said they still believe the ban will not protect young people.

They will soon contact the owners of more than a million underage accounts to help them prepare for the change.

Under the Australian law, platforms must take “reasonable steps” to block users aged less than 16 or face a fine of up to A$49.5 million.

“We don’t agree, but we accept and we will abide by the law,” said Jennifer Stout, Snap’s senior vice president of global policy and platform operations.

Ella Woods-Joyce, TikTok’s public policy lead for Australia, said, “TikTok will comply with the law and meet its obligations. We are on track to meet our compliance.”

Mia Garlick, Meta’s policy director for Australia and New Zealand, said the company would soon approach holders of accounts confirmed to be under 16 about 450,000 across Instagram and Facebook to give them a choice between deleting their photos and other data or offering to store it until they turned 16.

TikTok, which says it has 200,000 under-16 accounts in Australia, and Snap, which says it has 440,000 under-16 accounts, said they would take similar steps.

The companies added that they would use automated behaviour-tracking software to determine if an account holder claiming to be over 16 was underage.