Nicaragua's government said imprisoned Catholic bishop Rolando Alvarez was in adequate health following a medical checkup, as Washington called Tuesday for the religious dissident's release amid a wave of priest arrests in the country.

"The doctor reported that Rolando Alvarez's vital signs and state of health are fine. He did not undergo blood tests because he had eaten food," authorities said in a communique published in the pro-government media.

Alvarez, arrested in August 2022, has been a critic of President Daniel Ortega. Last February he was sentenced to 26 years in jail for treason, one day after refusing to board a US-bound plane carrying political prisoners into exile.

The government said a "medical examination" of Alvarez was carried out by doctor Yesser Rizo in the presence of police general commissioners Zhukov Serrano and Luis Barrantes.

Alvarez remarked during the exam that "he feels well and keeps exercising," according to the communique.

The government website, El 19 Digital, published a photograph of the bishop next to a doctor.

In a statement Tuesday, the US State Department slammed Ortega saying he has "unjustly incarcerated Bishop Alvarez for 500 days," during which authorities have kept him "in isolation, blocked independent evaluation of the conditions of his imprisonment, and released staged videos and photographs that only increase concerns about his well-being."

Fourteen Nicaraguan priests have been arrested in the latest crackdown on the Catholic Church in the Central American country, beginning on December 20 with the detention of Bishop Isidoro Mora.