There have been multiple reports that the Australian Government is considering blocking access to overseas websites that sell goods and services to Australians, but do not collect/forward GST to the Australian Tax Office.

However, Treasurer Scott Morrison (via a spokesperson) has apparently denied this is the case, stating that although the ATO has the power to block access to overseas websites for Australian visitors, it has never used this power because it is generally aimed at preventing the serious criminal activity, fraudulent sites and national security threats.

That really isn't much of a denial.  New laws are coming into effect in 2017 requiring that foreign businesses with over $75,000 of turnover in Australia collect GST from customers and forward it to the Australian government, even if the value of goods is lower than the current value of $1,000 at which GST is currently collected as goods arrive in the country.