The rapper Luaty Beirao and 14 other activists, all belonging to a youth opposition movement, were arrested in June, as they were peacefully gathering to protest against the current President, Eduardo dos Santos, who has been in power for 36 years.
Accused of plotting to oust the president, they have been held without trial for more than three months, which is the maximum allowed under Angolan law.
On September 21, a day after the three-month detention period expired, Beirao went on hunger strike.
Some say the reasons behind the activists' arrests are uncalled for.
"What is also critical about this case, is the fact that Angola has over 120 000 soldiers in its army, and the presidential guard is one of the largest in Africa. So how could 15 young activists, who were only reading books, and discussing the content of those books, possibly have staged a rebellion?" Rafael Marques, a journalist and anti-corruption activist, told RFI.
"Another critical element of this case is the fact that Beirao and some of these activists have been the most tortured since Angola achieved peace. They've been repeatedly assaulted by the police, beaten, Luaty had his head cracked a number of times by pro-government militia, by the police," Marques said.
And this is not the first protest the government has ended abruptly.
"We are very concerned. What we are seeing right now is that a repression of peaceful protests, including human rights defenders, is on the rise in Angola," Alexandra Poméon O'Neill, the head of the Observatory for the Protection of Human Rights Defenders told RFI.
"Recently, another human rights defender, Jose Marcos Mavungo, was sentenced to six years in prison on charges of rebellion. So what we are seeing is that the current government is becoming paranoid of a dynamic civil society, with zero tolerance for criticism."
On paper, Angola is a wealthy, oil-rich country. It's the third richest economy in Africa. But yet, half the population still survives on less than 2 euros per day.
Amnesty International has been following the case of Beirao closely. "That is one of the paradoxes that young people in Angola are raising. They are asking why a country that is rich in natural ressources is so poor in human development. Angola faces unemployment, poverty and inequality. And these affect young people fundamentally. And that is why since the last couple of years, we have seen more and more activism coming from young people who are questioning consumption, the production and the distribution of national wealth in the country," the director of the Southern Africa division, Deprose Muchena told RFI.
"And for asking those questions, they are getting persecuted. And I think we'll be seeing more and more of this until the Angolan authorities understand that to deal with the problems of young people protesting against the government, you address the economy. We expect better from a country that big, that wants to be taken seriously on the world stage."
More and more human rights groups are becoming increasingly outspoken against it. And foreign governments, especially the United States and some in Europe, are becoming more aware as well. "There was a European parliament report on Angola that criticised the government's human rights record," Alex Vines, the head of the Africa program at the Royal institute of international affairs in London, told RFI.
"A number of international delegations have been in Luanda recently and as part of their conversations with the Angolan goverment have raised their concerns about good governance and human rights. There's clearly been an exchange of views of these issues. Western countries in particular are concerned about what they see as a deterioration of human rights in Angola today."
Luaty Beirao has been joined in his hunger strike by a fellow activist.
It remains unclear if and when a trial will take place, but the 15 detained activists face up to 12 years in jail if convicted.