The police treatment of detainees was condemned on Wednesday by the Maldives United Opposition, as a crackdown continues under a state of emergency.
There are a dozen people in custody after anti-government protests last weekend.
The MUO said detainees were being given stale or rotten food and had no access to clean drinking water.
“Medication for pre-existing conditions, or new ailments after getting arrested, is not given on time,” it added
There have been frequent protests in the capital demanding the release of high-profile prisoners, with the police detaining opposition lawmakers and even their relatives.
Adam Zalif, the younger brother of Ahmed Ilham MP, was arrested around 10 pm on Tuesday after being summoned by police earlier that afternoon.
Police also searched his home without a warrant, but his family told Mihaaru that nothing was confiscated.
Ilham was arrested in connection with an alleged coup plot that President Abdulla Yameen said lay behind his decision to declare a state of emergency.
It has now been extended for an additional 30 days following a controversial vote in parliament on Tuesday.
MP Ali Hussain, who was detained and released on Saturday, is facing charges of obstruction of police duty, creating discord and for using foul language with the police.
Aminath Nadira, a supporter of former president Maumoon Abdul Gayoom, is also being charged with obstruction of police duty and assaulting an officer.
Photo: Auf Majeed