The US envoy, the statement said, remarked that Mr Gambaryan's freedom is of utmost importance for US diplomatic efforts.
The United States ambassador to the United Nations, Linda Thomas-Greenfield, has joined the clamour for the release of Tigran Gambaryan, an executive of Binance, the world's largest cryptocurrency exchange.
Mr Gambaryan has been in detention in Nigeria since February.
Ms Thomas-Greenfield made the request during a conversation with Nigeria's Minister of Foreign Affairs, Yusuf Tugar, at the ongoing 79th Session of the United Nations General Assembly in New York.
The US envoy remarked that the issue is of utmost importance for US diplomatic efforts."While further details regarding Gambaryan's detention were not provided in the official readout, this issue underscores the complexities of international relations and the role that diplomacy plays in protecting U.S. citizens abroad," the envoy added.
Mr Gambaryan, his colleague Nadeem Anjarwalla and Binance have been accused in Nigeria of laundering more than $35 million after authorities said the transactions conducted via their cryptocurrency platform contributed largely to the slump of the naira.
Mr Anjarwalla, who was seized alongside the former US Federal agent, escaped detention earlier in the year.
A couple of illustrious US diplomats, including Secretary of State Anthony Blinken, have sought Mr Gambaryan's release in private chats with top Nigerian Government officials, according to the New York Times.
They include President Bola Tinubu, Minister of Finance and Coordinating Minister of the Economy Wale Edun and Minister of Justice and Attorney General of the Federation Lateef Fagbemi.
Mr Gambaryan has been experiencing failing health in custody; his wife said in August, when she raised the alarm, that the deteriorating state of the herniated disc in his back could cause irreparable harm that could render her husband lame for life.
"As he is bed-bound, he is taking blood thinners to avoid blood clots, and the prison doctor has said that his muscles have atrophied," the family stated last month.
