Camagüey state authorities summoned Ricardo Fernandez Izaguirre on Tuesday and held him incommunicado for 29 hours.
Izaguirre's wife, Yusleysi Gil Mauricio asked about the charges against him and was reportedly "threatened and insulted" by three state agents, and told her husband would be "judged for being a counter-revolutionary".
Police refused to give any further information relating to Izaguirres' detainment or well-being after family had heard nothing about his case since he was taken into custody.
Speaking to religious freedom charity Christian Solidarity Worldwide (CSW) upon his release, he explained that he was held in a windowless cell that was "too small and uncomfortable for someone of my size."
Izaguirres' glasses were taken away from him and he was consistently transferred between his "intensely hot cell and an extremely cold interrogation room."
According to CSW, he was repeatedly threatened by various officials, including a Lieutenant Colonel and a Major throughout his interrogation.
Izaguirre, who has documented over 60 violations of freedom of religion or belief (FoRB) this year, was previously detained for four days in July, after meeting with members of the Ladies in White movement - who have been forcibly detained and prevented from attending church services and other religious activities by state authorities.
The Cuban government has ramped up attacks on FoRB and pressure on religious leaders since the adoption of a new constitution which severely weakened language on FoRB and freedom of conscience in February this year.
Concerns have been raised by Izaguirre that the authorities are attempting to fabricate a criminal case against him.
Neighbours and colleagues have also reported being questioned by Cuban State Security officers about the activist.
Izaguirre told CSW: "I have maintained my position and I maintain it today."
"They can do what they like with me but I won't stop defending Cuban citizens' rights to freedom of religion or belief."
CSW's Head of Advocacy Anna-Lee Stangl said: "While we welcome the release of Ricardo Fernández Izaguirre, he should never have been detained in the first place.
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