Luanda - Human rights groups in Angola on Wednesday denounced an escalation in police brutality against civilians since the start of the year in the oil-rich nation.
"In recent months we have seen high levels of police violence in Angola against peaceful protests, street vendors, journalists, activists and human rights defenders," a group of around 20 organisations said in a statement.
The groups criticised the "inhumane and cruel" treatment of prison inmates, after a video showing police and firemen beating prisoners in the capital Luanda was widely circulated on social networks.
"The police, who are supposed to protect us, commit the worst acts," Angelo Kapwatcha of university development group Fordu told AFP.
The broad coalition of human rights, environmental and development organisations across the country collaborate under an umbrella organisation, the Working Group for the Monitoring of Human Rights in Angola.
The country's interior ministry has condemned the violence and launched an inquiry to find the culprits.
Since the end of a civil war a decade ago Angola's economy has grown fast, and the country is now Africa's second-largest oil producer after Nigeria.
But most of its citizens live in poverty, and civil society groups as well as international organisations regularly complain of police abuse.
"Our political governance system was built on violence and the exclusion of the poor or those who are different. That is what we should attack," said Elias Isaac from pro-democracy group the Open Society Initiative for Southern Africa on Wednesday.
Angola's strongman President Jose Eduardo dos Santos has governed the country for the past 34 years. He won general elections in August 2012 - only the third since the country's independence in 1975.