The families of people arrested in Burundi this week over an alleged coup plot say their relatives have been tortured by intelligence agents.
Former Vice-President is among those arrested
The detainees' wives have been speaking on local radio stations, calling on the international community to help.
Communication Minister Karenga Ramdhan said the government was not aware of any reports of torture and would not tolerate any abuses of human rights.
A fifth man was arrested on Thursday over an alleged coup plot in June.
Earlier reports said six had already been arrested earlier in the week.
Ruth Magerano, wife of former Vice-President Alphonse Marie Kadege, said she saw her husband being abused while in detention.
"I saw him lying flat on the floor with a policeman standing on him - I saw this at a distance because they had left the door open, and they then closed it," she said.
When she saw her husband later, she said "they had taken off his clothes and because they had broken his arm it was difficult for him to dress again".
Mrs Magerano said she was not against her husband being investigated but she insisted that this had to be done with respect for human dignity.
Politician Deo Niyonzima's wife, Natasha, said the clothes that her husband gave her to take home for washing had been torn and bore stains of shoe polish, presumably from the boots of policemen as they kicked him.
She also said that her husband could hardly stand when she saw him from a distance when she visited the prison on Wednesday evening.
The leader of the local human rights group, APRODH, Pierre Claver Mbonimpa, also said that he had reliable information that the people under arrest had been tortured.
The arrests came after the security forces investigated reports that a rebellion had been planned for 30 June, Mr Ramadhan told the BBC earlier this week.
This followed a clampdown followed the shelling of the capital, Bujumbura, in mid-June, by FNL-Palipehutu, the last active rebel faction, which was not party to last year's peace deal.
Aleen Mugaravabona, head of FNL-Chanzo - a former rebel faction that signed the peace deal with the government - was among those arrested.
Since independence in 1961, Burundi has been plagued by tension between the dominant Tutsi minority and the Hutu majority.
In terms of the peace process, posts in the previously Tutsi-dominated army have been split equally between Tutsis and Hutus.
More than 300,000 people have died in the war sparked in 1993 by the assassination of Burundi's first Hutu head of state and democratically-elected president, Melchior Ndadaye.