(Adds details and background in paragraphs 2-6) Oct 27...

(Adds details and background in paragraphs 2-6)

Oct 27 (Reuters) - Australian billionaire Gina Rinehart-controlled Hancock Prospecting has taken an 18% stake in Azure Minerals (AZS) , it said on Friday, potentially hindering Chile's SQM SQMA.SN to take full control of the lithium developer.

SQM, the world's second-biggest lithium chemicals maker, already has a 19.99% equity stake in Azure and, on Thursday, offered to buy the remaining shares for $900 million.

One of the conditions of SQM's offer was that it would walk if any one shareholder took a stake of 19% or more in Azure.

Hancock Prospecting's statement did not mention when it had acquired the shares in Azure.

Hancock, Azure and SQM did not immediately respond to Reuters' request for comment.

Rinehart had used a similar tactic to make Hancock the top shareholder in lithium miner Liontown Resources (LTR) and scupper U.S. mining giant Albemarle's ALB.N A$6.6 billion ($4.19 billion) buyout offer.

SQM first bought its stake in Azure for A$20 million in March and had previously offered to buy out the company in an A$901.4 million deal that the lithium company rejected.

($1 = 1.5765 Australian dollars)