The amount of agricultural land owned by Chinese interests has soared above 3 million hectares, more than double the 1.46 million declared by the Australian Taxation Office last month, according to a Fairfax Media analysis of reported land sales.

The bulk of the growth arises from a recent series of significant sales in Western Australia – purchases that were not covered by the ATO foreign ownership register, which only dealt with registrations up to June 30, 2016.

But a compilation of reported land sales, endorsed by agribusiness experts, suggests that even at that date Chinese investors held about 2 million hectares of farmland, calling into question the efficacy of the register.

The 1.46 million figure was almost eclipsed by just two of the largest properties: the 705,000-hectare Wollogorang and Wentworth station on the Queensland/Northern Territory border, and the 639,500-Balfour Downs and Wandanya station in Western Australia, both owned by Chinese ball bearing billionaire Xingfa Ma.