Australia mining magnate Gina Rinehart has stepped into the takeover battle for Atlas Iron, after securing a blocking stake in company.
Atlas Iron on Wednesday confirmed Ms Rinehart's Hancock Prospecting, which operates the Roy Hill iron ore mine in Western Australia's Pilbara region, now controls a 19.96 per cent stake in the Pilbara miner.
Ms Rinehart's move follows a surprise play by Andrew Forrest's Fortescue Metals Group which last week invested $56 million to grab a 19.9 per cent stake in Atlas.
Atlas is currently the subject of a $280 million takeover bid from ASX-listed mid-tier player Mineral Resources, with a vote on the deal expected in July.
The Atlas board has supported the offer, which Mineral Resources has said will enable both companies to maximise the value of their low-grade iron ore deposits in a tough export market that is increasingly focused on premium ores due to stricter emissions controls on Chinese steelmakers.
CommSec market analyst Juliana Roadley says with an almost 20 per cent stake each, Fortescue and Hancock Prospecting's opinions will now weigh heavily on the takeover decision.
Fortescue Metals has already said it will not support the Mineral Resources proposal, while Hancock is yet to speak publicly on the deal.
"A lot of this asset is now in corporate hands rather than the market," Ms Roadley said.
"It is early days so we will have to wait and see if anyone else throws their hat in the ring."
Trading in Atlas Iron shares has been heavy in recent days: more than 850 million shares changed hands on Tuesday - equal to about nine per cent of the company's listed stock.
Almost 1.2 billion shares were traded on June 8, and more than 2.3 billion shares were traded on June 7, the day Fortescue Metals bought a 15 per cent stake.
Ms Roadley said the takeover bid by Mineral Resources announced in April triggered interest from other, larger operators in the Pilbara region looking at the quality of Atlas Iron's assets and the company's all-important rail and ports access.
Atlas operates two iron ore mines in the Pilbara, owns two undeveloped projects, and has an interest in the construction of a port facility capable of handling 50 million tonnes of exports each year.
"A lot of people are looking at the quality of the asset and their location to the actual mines and resources," Ms Roadley told AAP.
"There has been a lot of money on rail access, port access and all of that is up and running so it would be a good fit for Fortescue or Gina Rinehart's company."
Atlas shares rose 0.25 cents to 4.45 cents on Tuesday, while Fortescue shares dipped nine cents, or 1.9 per cent, to $4.55, in line with falls across the broader mining sector.