A media rights group says the number of journalists jailed worldwide is at a 15-year high, with Iran, Eritrea and China leading the list.

The Committee to Protect Journalists report released Thursday says 179 writers, editors and photojournalists were jailed worldwide as of December 1 compared to 34 detentions at the same time last year.

The U.S.-based group says Iran put 42 journalists behind bars, leading the list of the world's worst jailers for a second year. Iran was followed by Eritrea with 28, China with 24, Burma with 12, and Vietnam with nine.

The CPJ says the number of journalists jailed in the Middle East and North Africa has increased 50 percent over last year.

The group says the regime crackdown in Syria accounted for part of the increase, with eight journalists held.

The Committee to Protect Journalists says reporters have been mostly taken into custody on anti-state charges followed by violations of censorship rules.

The CPJ says the latest total of jailed journalists does not include those who are unaccounted for or abducted by criminal gangs or militant groups.