A consortium of the global tech superpowers, including Google, Facebook and Amazon, also argued that it would damage Australia’s relations with other countries because it would require “proactive” surveillance of all users worldwide, while criminalizing content reposted by users without the companies knowing about it.

“This law, which was conceived and passed in five days without any meaningful consultation, does nothing to address hate speech, which was the fundamental motivation for the tragic Christchurch terrorist attacks,” said Sunita Bose, the managing director of the Digital Industry Group Inc., an advocacy group representing Facebook, Google and other companies.

“With the vast volumes of content uploaded to the internet every second,” Ms. Bose said, “this is a highly complex problem that requires discussion with the technology industry, legal experts, the media and civil society to get the solution right — that didn’t happen this week.”

In the Senate Wednesday night, Richard Di Natale, a senator in the Australian Greens party, said the process was being rushed. He blamed both Australia’s conservative government and the opposition Labor Party, which he characterized as compliant.

“We’ve got some of the most significant changes to social media online regulation that we have ever seen,” he said. And yet, with little or no time for public input, he added, “it’s going to be rammed through.”

Experts warned that the law — which is meant to reach beyond traditional social media to sites that have been hotbeds of white supremacy, like 4Chan — could lead to legal challenges. It’s not clear whether Australia would be able to take action against companies that do not have offices in the country, nor is it clear if it would have a right to impose profit-based penalties on international behemoths like Facebook.