Ethiopia says it is releasing nearly 10,000 people detained under its ongoing state of emergency but plans to charge almost 2,500 others accused of destabilising the country.

Authorities have held about 12,500 individuals since declaring the state of emergency on October 9 after months of anti-government protests in the Oromia and Amhara regions.

Human rights groups, which accused the government of using excessive force in the protests, said hundreds were killed in the demonstrations in some of the country's worst violence since the ruling party came to power in 1991.

Under emergency rule, detainees could be sent to rehabilitation centres without charge, the government had previously said.

"[The detainees] have been given lots of trainings that were meant to give them lessons so that they won't be part of the destructive trend that we have seen in the past," Zadig Abraha, government spokesman, said on Wednesday.

"The state of emergency has brought about a tremendous change in the peace and security of the country. We have now returned to the status quo that we had before the violence."

The mass release began amid growing concerns for the health of those arrested and calls from the international community for the government to release political prisoners.

On Tuesday, Samantha Powers, US ambassador to the UN, in a tweet called on the Ethiopian government to release leaders of the opposition Oromo Federalist Congress.

The New York-based Human Rights Watch has accused security forces of killing more than 500 people in the unrest since November 2015.

The government, which is led by the Ethiopian People's Revolutionary Democratic Front, has disputed that number but has denied UN requests for an international monitor.

Hailemariam Desalegn, Ethiopia's prime minister, denied in October that the police used extreme violence against protesters, but vowed that the the government would investigate reports of excessive force.

The state of emergency included curfews, social media blocks, a restriction on opposition party activity, and a since-lifted ban on diplomats travelling more than 40 kilometres outside the capital without approval.

Year of protests

Ethnic Oromos initially took to the streets in Oromia to protest against proposed land seizures that would add to the area of Addis Ababa and force farmers from their land surrounding the city.

Protesters said the plan would also expand the capital's administrative control into the territory.

The demonstrations soon spread to the Amhara territory in the country's north, where locals argued that decades-old federal boundaries cut off many ethnic Amharas from the region.

Protesters called on the government to end arbitrary arrests and respect regional autonomy and constitutional rights.

Demonstrators took to the streets with renewed passion following a stampede during a protest at a religious festival in the town of Bishoftu, around 40km south of Addis Ababa, on October 3.

WATCH: What is triggering Ethiopia's unrest?

At least 52 people were crushed to death trying to flee when security forces fired tear gas into the crowd.

In the following days, protesters torched several mostly foreign-owned factories and other buildings which they claimed were built on seized land.

The unrest has been inflamed by underlying ethnic tensions. The Oromo and Amhara ethnic groups make up 60 percent of Ethiopia's population.

Both groups say that the ruling coalition, which has been in power for a quarter of a century, is controlled primarily by the Tigray ethnic group, who accounts for only 6 percent of the country’s population.

Protesters have alleged that the majority population of the Oromos and Amharas has created a natural threat to the government, who they say has repressed them in response.

German Chancellor Angela Merkel had urged Desalegn to allow for the protests and said police response should be proportional during a visit to Addis Ababa two days after the beginning of the state of emergency, which is expected to last through April.

File: An injured protester in October waits for help in Oromia region [Tiksa Negeri/Reuters]