The multibillion dollar plan by Japan's Nippon Steel to acquire US Steel may have run into another obstacle.

US Treasury Secretary Janet Yellen said she understands the views of President Joe Biden in opposing the takeover.

Yellen chairs the Committee on Foreign Investment in the United States, a body studying the implications of the proposed acquisition on national security.

Yellen said: " I certainly accept the president's view, which he has stated, that the company should remain in American hands. He hasn't said specifically that it's an issue of national security, but one that has to do with the good of the workers and the country."

Speaking on Tuesday, Yellen declined to comment on cases under review by the committee, citing the confidentiality of the process.

Last month, Biden said it's vital that US Steel remain an American company domestically owned and operated.

Despite this, US Steel shareholders on Friday approved the takeover offer by the Japanese rival.

It's unusual for a sitting president and the head of the Committee on Foreign Investment to comment on a proposed takeover before the committee makes a decision. This shows the sensitivity of the issue in the US during an election year.

Former President Donald Trump has stated that if he is reelected, he would block the deal.