Treasurer Scott Morrison has forced the sale of seven properties, worth almost $10 million in total, that are considered to have been acquired in breach of Australia's foreign investment rules.

The properties to be sold include a $5.2 million Hawthorn East mansion.

The owners of the properties have 12 months to sell, rather than the 3-month rule which was in place until May this year. Owners are still able to come forward voluntarily.

The Coalition has now forced 19 sales since it came to power.

Treasurer Scott Morrison said, "The Government's transfer of responsibility to the ATO for compliance has enabled more active investigations and actions targeting illegitimate purchases."

The Foreign Investment Review Board's work has recently been backed up with the support of 50 ATO staff, and new data matching technologies are being employed.