MUMBAI: Rupert Murdoch's News Corp Ltd. Today took preventive action in a bid to insulate itself against any hostile bid from the US cable company Liberty Media Corp.

The News Corp plan envisages issuing stock options to dilute the stake of any predator, according to a Reuters report from Sydney.

John Malone's Liberty began a transaction last week that could increase its voting stake in News Corp. to about 17 percent from nine per cent, raising speculation it could launch a takeover bid for Murdoch's media empire.

Realising that Liberty's Malone could make a hostile bid on an empire that Murdoch has built for his children, News Corp announced on Monday it would give its shareholders the right to buy one News Corp. share at half price for each share they own, if any party buys a 15 percent stake in the company. Shareholders would be able to buy up to $80 of half-price shares.

The strategy would exclude the purchaser of the 15 per cent stake, providing a "poison pill" defense against anyone plotting to take control of News Corp. from 73-year-old Murdoch and his heirs apparent, sons Lachlan and James.

"It means it's very much more expensive for Malone to maintain his position or extend his position in the company and he has to make the judgment as to whether it's worth it or not," Reuters quoted Michael O'Sullivan, president of the Australian Council of Superannuation Investors, which advises pension funds on corporate governance issues saying.

The existing holdings of Malone, a long-time ally of Murdoch, would not trigger the rights plan, but additional shareholdings would.

"The logic is to stop anyone acquiring the company or if they're going to acquire the company, they have to go and speak to the Murdoch interests. It locks the company up effectively," an analyst who refused to be named told Reuters.

According to News Corp said its move was prompted by Liberty's decision to engage investment bank Merrill Lynch in a hedging transaction for more than 80 million News Corp. Class B shares.

"There was no communication with the company about that decision before it was made, and it's too early to tell what Liberty's intentions are, but we're not necessarily treating them as friendly," said News Corp. spokesman Greg Baxter.

Could a Malone takeover change strategy for News Corp's pan-Asian venture, Star group, including the profitable venture in India? Difficult to say, but a new owner is certain to have his or her own vision, which could result in some expansions lined by Star India to be put in the cold storage.

But that is a big if, considering Murdoch is unlikely to give up control over an empire that he has built up so assiduously.Murdoch has groomed sons Lachlan, News Corp.'s deputy chief operating officer, and James, BSkyB's chief executive, to eventually run News Corp.