The Treasury Department is pictured in Washington, U.S., April 25, 2021. REUTERS/Al Drago/File Photo

SAO PAULO (Reuters) -The U.S. Treasury Department has asked Brazilian banks about measures they are taking under the Magnitsky Act, a source familiar with the matter said on Wednesday, weeks after Washington imposed sanctions on a top Brazilian judge.

Banco do Brasil, Bradesco, Itau, Santander and BTG received the notice, the source said, describing the message as generic, with standard wording citing the Magnitsky Act. The law is designed to impose economic penalties on foreigners deemed to have a record of corruption or human rights abuse.

Banco do Brasil, Itau Unibanco, BTG Pactual and Bradesco declined to comment. Santander Brasil did not respond to requests for comment.

Brazilian newspaper Folha de S.Paulo first reported that the Treasury's Office of Foreign Assets Control (OFAC) had sent the notices inquiring what actions the banks had taken, or were taking, to comply with the law.

The U.S. Treasury regularly engages with financial institutions to clarify compliance expectations, a spokesperson told Reuters, adding the department does not comment on private correspondence with them.

Under OFAC rules, U.S. persons and transactions in or routed through the United States are generally barred from dealing with property or interests of sanctioned individuals or entities unless authorized by a general or specific license, the spokesperson said.

The U.S. sanctioned Supreme Court Justice Alexandre de Moraes in late July, accusing him of authorizing arbitrary arrests and curbing free speech. Moraes oversees the case in which former President Jair Bolsonaro is accused of plotting a coup after losing the 2022 election.

The sanctions freeze Moraes' assets in the United States and bar U.S. companies from doing business with him, raising questions over potential spillovers for Brazilian banks with U.S. operations.

That uncertainty grew after Justice Flavio Dino ruled that foreign laws and decisions do not apply automatically to Brazilians inside the country.

(Reporting by Paula Arend Laier; additional reporting from Marcela Ayres in Brasilia; Editing by Rosalba O'Brien and Sonali Paul)