Two leading U.S. senators have called on President Joe Biden to use powers under a bill they authored to impose sanctions on those responsible for forcing the closure of Hong Kong’s Apple Daily newspaper, suggesting foreign banks were among those implicated.

The letter from Senator Pat Toomey, Republican ranking member of the Senate Banking Committee, and Democratic Senator Chris Van Hollen, a committee member, referred to a Reuters report last month that Hong Kong Security Secretary John Lee sent letters to Apple Daily owner Jimmy Lai and branches of HSBC and Citibank threatening up to seven years’ jail for any dealings with the billionaire’s accounts in the city.

Lee had ordered the branches to freeze Lai’s accounts, “which they appear to have done,” said a text of the senators’ letter made available to Reuters. It said some 500 police officers earlier this week raided the Apple Daily’s offices and arrested its executives and Hong Kong’s Security Bureau then ordered Apple Daily’s banks to freeze the newspaper’s assets, “directly resulting in its closure.”

The senators said their Hong Kong Autonomy Act passed last year required the U.S. secretary of State to identify to congress any foreign person, including foreign businesses “materially contributing” to the “inability of the people of Hong Kong to enjoy the freedom of assembly, speech, press, or independent rule of law.”