Amnesty International (AI) is raising the alarm over the jail conditions for Mozambican journalist Amade Abubacar.
AI said in a statement that the ill-treatment Mr Abubacar was subjected to included being denied food, medical treatment and visits by family members.
"Allegations that Amade Abubacar is being ill-treated and denied medical treatment must be investigated thoroughly and transparently and all those suspected of criminal responsibility brought to book," the statement quoting the AI Regional Director for Southern Africa, Mr Deprose Muchena, said.
The human rights group also called for Mr Abubacar's immediate and unconditional release.
Prisoner of conscience
Mr Abubacar was detained for reporting the suffering wrought on civilians by deadly attacks in Cabo Delgado.
According to AI, Mr Abubacar, who works Nacedje Communitary Radio in Cabo Delgado, is a prisoner of conscience, who was being detained solely for exercising his right to freedom of expression.
He was arrested on January 5 for documenting the deadly attacks by armed groups against civilians in Cabo Delgado province. Cabo Delgado is the northernmost province of Mozambique and borders Tanzania.
The attacks have escalated since the beginning of October 2017, with more than 100 people killed and hundreds of others having fled their homes.
AI said it had been reliably informed that Mr Abubacar was suffering from health problems, including constant headaches and diarrhoea.
Prior to his arrest, Mr Abubacar was in good health.
Mr Muchena was further quoted saying that Mr Abubacar's detention was an affront to media freedom and now the authorities seemed intent on compounding that shocking injustice by keeping him in jail.
The representatives of the Mozambican Bar Association on January 25 visited Mr Abubacar at the prison alongside his lawyer.
However, he was denied any private consultation with the representatives during the visit.
As part of a strategy to suppress media attention on the attacks, believed to be carried out by members of a local armed group known as Al-Shabab, Mozambican authorities have arbitrarily detained journalists reporting the story.