A report from African Union (AU) calls for an international police force, more military and human rights observers to be deployed into Burundi.
Hundreds of people have been killed since Burundi's President Pierre Nkuruniza announced his decision in April 2015 to run for a third-term.
Nkurunziza won a disputed election in July, which triggered the uprising across the country. The violence caused more than 260,000 people to flee, fearing possible genocide.
The AU rights investigators said it was "necessary that, apart from strengthening AU human rights monitors and military observers, an international police mission is deployed."
Last year the AU's proposal of deploying a 5000-strong peacekeeping force was rejected during a session.
The AU said the international police force would help boost security and ensure "protection of people in those areas most affected by violence and which continue to witness it."
The AU investigators also called for the "reopening of the various independent radio stations that were arbitrarily closed down" and to "reverse the collective closure of the 10 civil society organisations that play a key role in the promotion and protection of human rights."
The report was based on a week-long visit to the country in December 2015.
During the investigation, delegates from the African Union were given limited access by Burundian forces due to "an eruption of major fighting" in the capital Bujumbura.
A mission team from the UN High Commissioner for Human Rights started its a four-month investigation earlier this month.
Five months ago UN Human Rights Council in Geneva called for a team to be "urgently" sent to the country, as concerns have grown that Burundi is at risk to find itself facing civil war once again.