Elliott Associates has bought shares in Samsung Fire & Marine Insurance Co Ltd, a spokeswoman for the South Korean firm said, potentially strengthening U.S. hedge fund's hand in its bid to block an $8 billion proposed merger of another two Samsung Group units.

Samsung Fire & Marine is a shareholder in Samsung C&T Corp, the company Elliott wants to prevent being taken over by Samsung Group de facto holding company Cheil Industries. The $8 billion deal is seen as a key step in securing the leadership transfer for the sprawling family-run conglomerate.

Elliott recently bought a one percent stake in each of Samsung Fire & Marine and Samsung SDI Co Ltd, another shareholder in C&T, for about 200 billion won ($178 million) in total, the Chosun Ilbo daily reported earlier, citing unnamed banking and industry sources.

The Fire & Marine spokeswoman confirmed the purchase, but did not give details. Both Samsung SDI and Elliott declined to comment on the matter.

Elliott is the third largest shareholder in C&T with a 7.1 percent stake.

Park Ju-gun, head of corporate analysis firm CEO Score, said the investments give Elliott more leverage over the fate of the Cheil-C&T deal, and ultimately, Samsung Group's restructuring, which gathered pace after 73-year-old patriarch Lee Kun-hee suffered a heart attack last year and remains in hospital.

"Samsung Group has no certainty over Chairman Lee Kun-hee's condition, so they are trying to wrap up the restructuring process within this year and I think Elliott knows that," Park said.

Under South Korean law, an investor with an at least one percent stake can sue the company's directors and is able to see who the other shareholders are.