The Coalition for Human Rights in Fiji says the country's enforcement and security forces should not use the Covid-19 pandemic as an excuse for human rights violations.
The coalition said this followed allegations of assault by Corrections officers and the death of a prisoner in Suva last week.
Coalition chair Nalini Singh said the situation was even more troubling at a time when hundreds of people were being arrested for breaching the nationwide curfew.
Singh said the rights and dignity of those detained should be protected.
"The Covid-19 pandemic is not an excuse for human rights violations. Excessive force and brutality are unacceptable from any of our enforcement or security forces."
Singh said proper advice should be given to anyone arrested or charged with offences under the Public Health Act.
Ms Singh said the death of Jone Masirewa was a concern and she called for the procedures on dealing with detainees to be improved.
Police said Masirewa had been arrested in connection with a burglary and was at the Suva Remand Centre when he died last week.
Four corrections officers had been charged over the incident - two with murder and the other two with assault.
Singh said justice for Masirewa should start with an independent investigation.
"Whatever the cause for the arrest may have been, there is no need for corrections officers or any other security forces to be displaying such brutality that has led to a death."
Singh said results of the independent investigation should be made public.
She said Fiji had pledged its commitment to the United Nations Convention against Torture (UNCAT) and just returned from the Universal Periodic Review (UPR) in Geneva.
She said Fiji should be a world leader in upholding human rights.
Singh called on the government and police to ensure that the First Hour Procedure (FHP) is operational.
"The human rights of a detained person or of an accused person must be fully respected as guaranteed in the Fiji Constitution (2013) and especially protected during these times where multiple charges are placed daily on breach of restrictions on Covid-19."
Earlier, Fiji's Human Rights and Anti-Discrimination Commission said it was investigating the prisoner's death.
Director Ashwin Raj said any death that occurred in custody was a serious concern.
Raj said allegations by the victim's family that they were not informed of his death and detainment was "disconcerting and constitutes an interdiction of his rights as an arrested and detained person".
He said the commission was working with the corrections department and police to find out what happened.
Singh said the coalition welcomed Raj's comments that those arrested and detained had the right to be free from cruel and degrading treatment and must be afforded their rights guaranteed under section 13 of the Fijian Constitution.
'Culture of democracy'
The Coalition for Human Rights said corrections officers, police and the military should be reassuring the public and "there should not be any impunity for torture or murder by enforcement and security officers.
"During this pandemic particularly, there are understandable frustrations in dealing with disobedience of precautionary measures but enforcement and security officers are trained for these situations and have an obligation to remain within the perimeters of the law.
"There should be a continued effort at eliminating torture and brutality for Fiji to cultivate a culture of democracy that emphasises rule of law, accountability and equal protection of citizens' human rights," the coalition said.