New York -The Committee to Protect Journalists highlighted Nigeria and Brazil on Tuesday as among the worst offenders for violence against reporters - and failure to bring culprits to justice.
The New York-based media rights group issued its annual Impunity Index headed once again by Iraq, which has been a particularly deadly place for journalists since the US invasion in 2003, even if murders are currently in decline.
There are "more than 90 unsolved journalist murders over the past decade and no sign that authorities are working to solve any of them," the CPJ said.
Other longtime mainstays on the list include Afghanistan, Colombia, Mexico and Sri Lanka.
"Although Colombia has had modest success in solving murders, Afghanistan, Sri Lanka, and Mexico have failed completely in the prosecution of numerous past slayings. These law enforcement failures often lead to another pernicious problem: widespread self-censorship," the group said.
The CPJ especially cited Nigeria as "one of the worst nations in the world for deadly, unpunished violence against the press."
At least five journalists have been murdered because of their work since 2009 and Nigerian press freedom activist Ayode Longe told the CPJ that sloppy investigations have "emboldened others to assault journalists, believing nothing would be done to them."
The violence comes after a decade of relative security for journalists and the country enters the index for the first time, ranked 11, the CPJ said.
Another country taking a backward step, according to the CPJ, is Brazil, which moved up from 11th to 10th place on the blacklist.
Brazil "seemed to have turned the corner as recently as 2010, when it briefly dropped off CPJ's Impunity Index because of declining attacks and a number of successful prosecutions.
"But a three-year spree of murders -- many targeting provincial bloggers and online reporters, and all unsolved -- has shown the gains there to have been illusory," the CPJ said.
It said provincial towns were the most dangerous places because local groups with power over the police and judiciary were able to go unpunished, while in some cases the authorities themselves attacked journalists.
The impunity index rankings are as follows:
4. Sri Lanka
The whole index and details can be found here.