A total of 57 journalists were killed in connection with their work during 2010, Reporters Without Borders said in Berlin Thursday - but increasing numbers are being kidnapped to be held as bargaining chip.

The France-based group said that tally compared with 76 in 2009, a drop of 25 per cent.

"The number of journalists killed in war zones has fallen in recent years," the group said, compiling figures from its various offices.

"It is becoming more and more difficult to identify those responsible in cases in which journalists were killed by criminal gangs, armed groups, religious organisations or state agents."

Reporters Without Borders was founded in 1985 to advocate freedom of the press.

The group's head, Jean-François Julliard, said, "The authorities of the countries concerned have a direct duty to combat the impunity surrounding these murders. If governments do not make every effort to punish the murderers of journalists, they become their accomplices."

A distinguishing feature of 2010 was an increase in kidnappings of journalists. There were 29 cases in 2008, 33 in 2009 and 51 in 2010.

"For the first time, no continent escaped this evil in 2010. Journalists are turning into bargaining chips," the group said, adding that such attacks were most common in Afghanistan and Nigeria.

"Kidnappers take hostages in order to finance their criminal activities, make governments comply with their demands, and send a message to the public. Abduction provides them with a form of publicity," the report said.

Earlier this week, a different lobby group, the Press Emblem Campaign in Geneva, put the tally for 2010 at 105 journalists.

The campaign recorded deaths across a total of 33 countries, with Pakistan and Mexico being the most dangerous.