Amnesty International says at least 150 pro-Biafra protesters have been killed by security operatives in the south-eastern part of the country.
In a report released on Wednesday, the human rights body said many protesters were still being held incommunicado.
“In south-east Nigeria, security forces led by the military, embarked on a chilling campaign of arbitrary arrests, extra-judicial executions and enforced disappearances,” the report read.
“Many individuals are still being detained incommunicado while state security agents have killed at least 150 peaceful pro-Biafra protesters.”
Amnesty International also said there appears to be an attempt to suffocate freedom of expression, saying at least 10 journalists and bloggers have been arrested in recent times.
“The past year has also seen a disturbing rise in arrests and intimidation of media professionals and activists in Nigeria,” the report read.
“At least ten journalists and bloggers were arrested in 2016, some for alleged connections to Boko Haram.
“In January, members of the Nigerian army raided the editorial offices of Premium Times and arrested journalists Dapo Olorunyomi and Evelyn Okakwu. They were subsequently released but the move sent a clear message to intimidate journalists and the media.”
The report also said the conflict between Boko Haram and the Nigerian army has affected 14 million people in the region.
The human rights body added that two million people need urgent humanitarian assistance in the north-eastern part of the country.
“In Nigeria’s north-east, the ongoing conflict between the Boko Haram armed group and the country’s security forces has affected more than 14 million people, with two million in need of urgent humanitarian assistance,” the report read.
“The north-east of Nigeria descended into a major humanitarian emergency as a consequence of the conflict and the atrocities committed by all parties to the conflict. Once again, it is the poorest and most vulnerable people who pay the price.
“The armed conflict drove millions from their homes, leaving them living in squalid conditions in camps under heavy military guard and without adequate access to food, water and medical care. Throughout the year, hundreds died in these camps because of malnutrition.”