TOKYO - Japan's Nippon Steel on Monday reiterated its determination to challenge US President Joe Biden's decision to block its takeover of US Steel.

Nippon Steel President Tadashi Imai said in a statement issued Monday that "we will pursue every possible measure" as "we will never give up on expanding our US operations."

The Japanese steel giant, the world's fourth-largest by production volume, will hold a press conference on Tuesday, Kyodo News reported.

READ MORE: Biden blocks takeover of U.S. Steel by Japan's Nippon Steel

A Nippon Steel executive said that the company wants to confirm various issues ahead of the press conference, it added.

Meanwhile, Japan's Prime Minister Shigeru Ishiba on Monday called for clarity over Biden's block of the proposed acquisition, noting that "they need to be able to explain clearly why there is a national security concern."

Biden said Friday that he has decided to block the $14.1 billion sale of US Steel to Nippon Steel, citing risks to national security, while urging the two steelmakers to "fully and permanently" abandon their plan.

READ MORE: Biden to decide fate of Nippon Steel's $15b bid for US Steel

In a joint statement released after the decision, the two firms said the US authorities' review of the international buyout project was "manipulated to advance President Biden's political agenda" and that they will "take all appropriate action to protect our legal rights."