11:46 AM EDT, 07/10/2024 (MT Newswires) -- (Adds stock moves for US-based steel producers, more detail throughout).

The Biden administration said Wednesday that it will implement a "melt-and-pour" requirement for imports of Mexican steel products and will increase the section 232 duty rate for imports of Mexican steel and derivative steel products that are melted and poured in a country other than Mexico, Canada, or the US.

Under the new rules, steel arriving from Mexico but poured or melted outside North America will be subject to a 25% tariff. Mexican aluminum will be subject to a 10% tariff if melted or cast in China, Belarus, Iran or Russia.

Wednesday's joint statement by President Joe Biden and Mexican President Andres Manuel Lopez Obrador is intended to close a loophole that allowed China and other countries to sidestep tariffs by first routing steel and aluminum through Mexico before transporting it into the US.

"In my judgement, these measures will provide an effective, long-term alternative means to address any contribution by Mexican steel articles imports to the threatened impairment of the national security by restraining steel articles imports to the United States from Mexico, limiting transshipment, and discouraging excess steel capacity and production," President Biden said in the statement.

The Biden Administration announced the tariffs on Chinese steel and aluminum in April under its Section 232 authority in trade legislation adopted in 1962 allowing the president to impose tariffs or make other policy adjustments to protect US national security.

Shares of US steel producers were mixed following the White House announcement. North Carolina-based Nucor ( NUE ) recently was trading about 2% higher, extending its advance since starting Wednesday's session with a 0.5% gain.

US Steel (X) was off about 1.3%. The Pittsburgh-based steel company accepted a buyout offer on Dec. 18 from Japanese rival Nippon Steel valued at around $14.9 billion but is still waiting for approval from US regulators.

Shares of Cleveland Cliffs ( CLF ) , which last year also sought to acquire US Steel but was outbid by Nippon Steel, recently were edging 0.3% higher.

Price: 38.00, Change: -0.80, Percent Change: -2.05