WASHINGTON (Reuters) -The Biden administration delayed until June an order for Nippon Steel to abandon its $14.9 billion bid for U.S. Steel, the companies said on Saturday, giving them some time to revive the politically contentious deal.

President Joe Biden blocked the acquisition on national security grounds on Jan. 3, and Treasury Secretary Janet Yellen said this week the proposed deal had received a "thorough analysis" by the interagency review body, the Committee on Foreign Investment in the United States.

The delay will give the courts time to review a legal challenge the steelmakers brought against Biden's order. The parties previously had 30 days to unwind their transaction.

"We are pleased that CFIUS has granted an extension to June 18, 2025 of the requirement in President Biden's Executive Order that the parties permanently abandon the transaction," the companies said in a statement.

"We look forward to completing the transaction, which secures the best future for the American steel industry and all our stakeholders," they said.

June 18 is the expiration date of the current acquisition contract between Nippon Steel and U.S. Steel, according to a spokesperson for the Japanese company.

The White House, Treasury Department and a lawyer for the United Steelworkers union, which has opposed the deal, could not immediately be reached for comment late on Saturday.

Biden, a Democrat, and his incoming successor, Republican Donald Trump, both voiced opposition to the Japanese company acquiring the American steelmaker as the candidates courted union votes in the November election that Trump won.

U.S. Steel and Nippon Steel alleged in their lawsuit on Monday that the CFIUS review was prejudiced by Biden's longstanding opposition to the deal, denying them the right to a fair review. They asked a federal appeals court to overturn Biden's decision to allow them a fresh review to secure another shot at closing the merger.

The Treasury secretary chairs the CFIUS panel, which screens foreign acquisitions of U.S. companies and other investment deals for national security concerns. CFIUS normally decides directly on cases or submits recommendations to the president, but in the U.S. Steel-Nippon Steel case, the panel failed to reach consensus, leaving the decision to Biden.

CFIUS has rarely rejected deals involving the Group of Seven closely allied countries, which include Japan.

Japanese Foreign Minister Takeshi Iwaya said on Sunday he had told outgoing Secretary of State Antony Blinken during a recent meeting that Biden's decision to block the sale on national security grounds is highly regrettable.

"The broader context of the Japan-U.S. alliance is extremely important, and it is essential to handle this transaction appropriately to avoid disrupting it," Iwaya told a talk show on public broadcaster NHK.

"Japan is the largest investor in the United States. There is widespread unease within the business community, and I will continue urging the U.S. to alleviate these concerns," Iwaya said.