By Nate Raymond

BOSTON (Reuters) -A Russian-born scientist at Harvard University accused of smuggling frog embryos into the United States was indicted on Wednesday on additional charges nearly two weeks after her lawyers secured her release from U.S. custody.

Federal prosecutors in Boston said a grand jury returned an indictment charging Kseniia Petrova, 30, with one count of concealment of a material fact, one count of false statement and one count of smuggling goods into the United States.

Prosecutors had charged her in May only with smuggling. The two new charges add to her criminal exposure and were filed after her lawyers last week urged a magistrate judge to dismiss the initial criminal complaint.

Petrova's lawyers did not immediately respond to a request for comment.

Prosecutors secured the indictment after Petrova was granted bail on June 12. She had been detained for months after U.S. immigration authorities took her into custody on February 16 at the airport in Boston upon her return from a trip to France.

Her supporters said she was detained as part of the practice by President Donald Trump's administration of targeting international students and academics for visa revocations and detention as part of his hardline immigration agenda.

Prosecutors said U.S. Customs and Border Protection agents stopped Petrova, who works at Harvard Medical School, after her checked duffle bag was flagged for inspection, revealing the frog embryos.

Petrova has said her boss asked her to bring back frog embryo samples for experiments. But prosecutors said the embryos constituted biological material that should have been declared to customs officials at the port of first arrival. 

Prosecutors said that when she was approached by law enforcement, Petrova initially denied carrying any biological material in her baggage, and later claimed to be unsure she was required to declare the embryos when entering the United States.

But prosecutors said one of Petrova's colleagues had texted saying that she needed to make sure she got permission to bring samples back.

Petrova's visa was then canceled and immigration officials took her into custody with the intent of deporting her back to Russia, a prospect Petrova has said she feared after protesting Russia's war in Ukraine.

(Reporting by Nate Raymond in Boston; Editing by Leslie Adler)