Gina Rinehart's Hancock Prospecting has launched a joint bid with a Chinese partner for the nation's largest landholder, S.Kidman & Co, in what will be a further political test for Australia's foreign ownership rules and signals the biggest push so far by Australia's wealthiest businesswoman into agriculture.

Hancock will own 67 per cent of Kidman's giant cattle portfolio and Chinese conglomerate Shanghai CRED 33 per cent under the formal agreement announced late Sunday following months of speculation. While the involvement of a Chinese bidder will keep the deal in the political spotlight, it is the first bid for the pastoral empire by a consortium majority owned by Australian interests.