FILE PHOTO: A bronze seal for the Department of the Treasury is shown at the U.S. Treasury building in Washington, U.S., January 20, 2023. REUTERS/Kevin Lamarque/File Photo

MEXICO CITY (Reuters) -The United States on Thursday sanctioned a powerful faction of the Sinaloa Cartel and its alleged associates, including a ruling party federal lawmaker, as the U.S. ramps up pressure on Mexican crime groups and allegedly corrupt politicians.

The U.S. Treasury Department said in a statement it had designated the El Mayo faction of the Sinaloa Cartel, one of the most powerful wings of the sprawling crime group. It accused the faction of producing and trafficking fentanyl, the deadly synthetic opioid, as well as trafficking in other drugs like cocaine, marijuana, heroin, and methamphetamine.

"The Sinaloa Cartel is a foreign terrorist organization that continues to traffic narcotics, launder its proceeds, and corrupt local officials," said Under Secretary of the Treasury for Terrorism and Financial Intelligence John K. Hurley in the statement.

The sanctions also included five individuals and 15 companies that U.S. authorities say are linked to the El Mayo faction.

These included Hilda Araceli Brown Figueredo, a federal lawmaker representing Baja California for the ruling Morena party who was formerly mayor of Rosarito, a beachfront town about 15 miles south of the California border.

It has in the past been extremely rare for the U.S. to sanction sitting lawmakers in Mexico.

The U.S. Treasury Department accused her of having a close relationship with a cartel political operative, which gave the El Mayo faction control over parts of Rosarito municipal government and ensured protection for the group's criminal activities.

Brown, in a statement shared on social media, said: "I stand firm in any situation, before any authority. I will continue working as always."

The sanctions announcement came on the same day that Hurley is traveling to Mexico City to meet with Mexican officials.

The Trump administration has ratcheted up pressure on Mexican crime groups, particularly the Sinaloa Cartel, which is one of several such groups that the U.S. designated as a foreign terrorist organization earlier this year.

The U.S. has also pressured Mexico City to investigate and prosecute allegedly corrupt politicians with links to the cartels.

(Reporting by Diego Ore and Lizbeth Diaz, writing by Laura Gottesdiener)