U.S. President Joe Biden has decided to officially block Nippon Steel's proposed $14.9-billion purchase of U.S. Steel, a person familiar with the decision said on Friday, dealing what is likely a fatal blow to the contentious merger plan.

The Committee on Foreign Investment in the United States (CFIUS) had previously referred the decision to approve or block the deal to Biden, who will leave office on Jan. 20.

Biden's call to block the deal came despite contrary efforts by some senior advisers concerned that it could hurt U.S.-Japan relations, according to The Washington Post, which first reported the news.