The US is concerned about the health and safety of Niger’s elected president Mohamed Bazoum, who has spent more than two weeks under house arrest.
“We are greatly worried about his health and his personal safety and the personal safety of his family,” a state department spokesman said.
Earlier Mr Bazoum’s party said he and his family were being detained under “cruel” and “inhumane” conditions, Reuters reported.
Mr Bazoum was deposed on 26 July.
Since then, a military junta has ruled Niger while Mr Bazoum has been kept in the presidential palace. Members of the junta have made no comment about the ousted leader’s condition.
On Tuesday US Secretary of State Antony Blinken called Mr Bazoum assuring him of the US’s ongoing support, Washington said.
US State Department spokesman Matthew Miller added: “As time goes on, as he’s held in isolation, it’s a situation that is of growing concern to us.”
Mr Bazoum’s political party, PNDS-Tarayya, claimed in a statement that Mr Bazoum and his family had no access to running water, electricity, fresh goods or doctors.
The statement echoed previous comments made by Niger’s elected prime minister Ouhoumoudou Mahamadou, who has said Mr Bazoum was being held with his wife and son without electricity or water.