The 78-year-old was imprisoned 19 years ago by Myanmar's ruling junta for spreading "anti-government propaganda".

Reporters Without Borders and the exiled Myanmar media group, Burma Media Association, say Win Tin has lung problems and severe asthmatic attacks which prevent him from sleeping and eating properly.

"It will be exactly 19 years on July 4 since Burma's military arrested Win Tin," the groups said in a joint statement, referring to Myanmar by its former name.

"The government, which has a responsibility to protect the life of its citizens, should now release him. He should be moved to a hospital as quickly as possible."

Win Tin was sentenced to 20 years in Myanmar's infamous Insein prison where other political prisoners are kept.

The watchdogs said he has not been allowed any visits from the International Committee for the Red Cross since 2006, because he refused to work during his detention.

They say at least ten journalists and one blogger are imprisoned in Myanmar.

In June two editors were arrested for travelling to the cyclone-hit Irrawaddy Delta to help deliver relief supplies and bury the dead.

Aung Kyaw San, editor of the Myanmar Tribune, was arrested along with 16 other people, while sports writer and editor Zaw Thet Htwe was detained during a visit to his ailing mother, the organisations said. - AFP