2012 was the "deadliest year for journalists", said the International Press Institute on Monday, with the highest number of deaths recorded since the media watchdog began its annual tally.

The year had "been marked by an appalling and disturbing truth: an unprecedented 132 journalists were killed in the line of duty or as a consequence of their reporting in 2012", the IPI said in a statement posted to its website.

The previous highest figure had been 110 deaths in 2009. Last year, 102 journalists were killed.

"It is almost unbelievable that so many journalists have died this year," IPI executive director Alison Bethel McKenzie said.

At least 31 journalists and eight citizen reporters died in Syria alone in 2012, while 16 others died in Somalia.

The Vienna-based watchdog began tracking deaths in 1997.

Journalists were also killed in Brazil, Honduras, Mexico, Pakistan, the Philippines and other countries traditionally considered dangerous for the media.

Turkey was criticised for having the highest number of journalists in prison, with the tally at 70 people.

The watchdog also singled out a host of countries for restricting press freedom to varying degrees, including China, Cuba, Nepal and the US among others.

In positive developments, the IPI noted that Grenada had decriminalised libel and Myanmar abolished pre-publication censorship.

IPI's figures differ from that of other media watchdogs such as Reporters without Borders, as it includes not just targeted killings but all journalist deaths on the job.