U.S. lawmakers have called on President Joe Biden to take up the case of an American Binance executive detained in Nigeria.

In a letter sent to the White House, Secretary of State Antony Blinken and Special Presidential Envoy for Hostage Affairs Roger D. Carstens, House members including Michael McCaul (R-Texas), Chairman of the House Foreign Affairs Committee, urged "immediate action" in the case of Tigran Gambaryan, arguing that his "health and well-being are in danger."

Gambaryan, a U.S. citizen who heads up Binance's financial compliance unit, has been detained in Nigeria since February and faces charges of money laundering to the tune of $35 million.

In the letter, the U.S. House members describe the charges leveled against Gambaryan as "baseless," arguing that they constitute a "coercion tactic by the Nigerian government to extort his employer." Following the charges, Gambaryan should be considered a "U.S. Citizen wrongfully detained by a foreign government,” under the terms of the Robert Levinson Hostage Recovery and Hostage-Taking Accountability Act.A

Gambaryan has been held in the "notorious Kuje Prison, known for its harsh conditions," and denied access to his legal team without the presence of Nigerian government officials and armed guards, the letter notes. In a "deeply disturbing" recent development, the letter notes that Gambaryan collapsed in court and was subsequently hospitalized, but that the prison has failed to fully comply with the court order and that he has not received adequate health care.

The letter, signed by 16 members of Congress, urges that Gambaryan's case be transferred to the Office of the Special Presidential Envoy for Hostage Affairs, arguing that, "Immediate action is essential to ensure his safety and preserve his life."

Gambaryan and his colleague Nadeem Anjarwalla were detained in February after traveling to Nigeria at the invitation of the Office of the National Security Advisor (ONSA) and the Economic Financial Crimes Commission (EFCC) to discuss Binance's activities in the country.