SYDNEY, Oct 11 (Reuters) - Australian billionaire Gina Rinehart has taken a 19.9% stake in lithium miner Liontown Resources, her company Hancock Prospecting said on Wednesday, potentially hindering a takeover bid launched by U.S. mining giant Albemarle Corp.

Hancock has steadily built its stake since September, when Albemarle Corp lodged its bid for Liontown. The U.S. miner needs 75% support from Liontown investors who vote on the deal to succeed with its bid.

"Hancock now looks forward to having a prominent influence on Liontown's future as its largest shareholder," the statement said. Under Australian takeover rules, a single shareholder must declare its intention if its stake moves above 19.9%.

Hancock said it had not paid more than A$3 per share.

Liontown declined to comment, as did Albemarle.

Albemarle has offered A$3 per share for Liontown which values the company at $4.3 billion. The bid was made through a scheme of arrangement, and its success will depend on the outcome of a ballot of Liontown investors at a shareholder meeting.

A stake of between 15% and 20% can often become a blocking stake depending on investor turnout on the day of the ballot.

Albemarle's declared its bid 'best and final', which means the current offer cannot be raised and the bidder would have to walk away for some time before returning with a sweetened deal.

(Reporting by Scott Murdoch; Editing by Jacqueline Wong & Simon Cameron-Moore)