A U.S.-based human rights group says freedom of expression is under attack in Nigeria.
The New York-based Human Rights Watch says Nigerian authorities have been silencing their critics through arrest, detention, torture and even killings.
The main researcher for the report, Carina Tertsakian, says that even though Nigeria's government is now elected democratically, Nigerians still cannot express themselves without fear of grave consequences.
"What surprised me was the extent of the problem," she said. "We had been aware that there had been a few cases where journalists and political activists had been harassed by the government over the last couple of years, but what surprised me when I started digging into it was just the sheer number of cases where critics of the government, whether these are political opponents, journalists, human rights activists or just ordinary Nigerians who were criticizing the policies of the government have been targeted in various ways, intimidated, harassed, arrested, detained and in the worst cases tortured or even killed."
She says she believes Nigeria's government escapes criticism by other governments because it is an important oil supplier.
The document highlights examples such as one concerning a journalist in charge of his newspaper's Rivers state office, who was beaten on his way to work last month after reporting about alleged corruption by the state's deputy governor.
In another recent case, three journalists were arrested and charged with sedition in Lagos several weeks ago after reporting that high-ranking members of the federal government were involved in large-scale theft of crude oil.
The report's release on Tuesday came just several days before Nigeria's capital, Abuja, is about to begin hosting the Commonwealth summit on Friday.
Eight years ago, the much-publicized execution of the Ogoni ethnic minority activist Ken Saro-Wiwa led to Nigeria's being suspended from the grouping.
Nigeria was readmitted in 1999 following its return to civilian rule.
A spokesman for the federal government responded to Tuesday's report, saying democracy in Nigeria needs support and encouragement, rather than what he called opposition at all costs.