As many as 150 of the loggers are trying to defect to South Korea, according to government sources in Seoul. North Korea angrily denies the reports, describing them as 'rumour, unfounded propaganda and sheer fabrication'. But one of the escapees, contacted this week in the Russian Far East city of Vladivostok, said economic hardship at home and bad living conditions in the camps were driving many of the loggers to think seriously of defecting.
Park Dong Bok, who comes from the northern part of North Korea, close to the Chinese border, had been working for two years in one of the Siberian timber camps close to the city of Khabarovsk. Although on Russian territory, the 16 camps are run entirely by North Koreans, watched over by Pyongyang's notorious security police who confiscate passports so workers cannot travel, even within Russia. Russian officials are not allowed inside the camps, despite reports of serious abuses, but they tolerate this because the North Koreans are an exceedingly cheap labour force. A portion of the timber is given to Russia and the rest goes to North Korea.
Mr Park is 36, and like all the lumberjacks in Siberia - estimated at between 15,000 and 20,000 - he has a wife and family back in North Korea. The loggers' families act as virtual hostages to discourage defection attempts.
Though the workers initially volunteer to come to Russia, conditions are reminiscent of Stalin's forced labour camps of the 1950s. Life is unpleasant, particularly in the winter when there is no heating - though food rations were better than at home, said Mr Park: the loggers received rice every day, meat twice a month - usually pork imported from China - and grew their own vegetables. In North Korea most people receive meat only on a few feast days, and rice is often replaced with low-quality cornmeal.
But discipline in the camps was harsh, he said. There were frequent beatings by camp guards, and two types of prison: a log house for minor infractions and solitary confinement cells for 'ideological crimes', such as criticising the government of Kim Il Sung. The loggers dreaded these prisons: sleep was impossible, rations were reduced, beatings were commonplace and not all prisoners got out alive. The work day began at 5am, and continued until 8pm in the summer, 5pm in the shorter winter days. Rest days were rare. Each logger received one new set of clothes per year, and most worked for three years before returning home. They earned an average of dollars 25 a month (paid in North Korean won), and those able to cut 50 per cent more than their target could earn a maximum of dollars 40 a month.
To supplement their income, some of the loggers secretly distilled alcohol in the forest and sold it to Russians who came to the perimeter fences at night. Russian prostitutes also arrived at night.
Mr Park was driven to defect by news from home. Because his father had retired, his family's food ration had been reduced, and to supplement their diet his mother started dealing on the black market. She was discovered, and the family was deported to a poor mountain area as punishment. His wife divorced him and took her two children with her.
With nothing to hold him back, Mr Park decided to escape and seek asylum in South Korea. Other North Koreans he worked with escaped because of hardship at home, and the news about the outside world that they received from illicit contacts with Russians. Since South Korea opened a consulate in Vladivostok last year, the North Koreans have made this city their first destination: it is several hundred miles from the logging camps, compared with the 5,000-mile journey to the next South Korean diplomatic post in Moscow.
Mr Park, who speaks a little Russian, is hiding in Vladivostok until his asylum request is processed. He is afraid North Korean agents will track him down. The South Korean government is still debating whether to accept the asylum requests. Normally Seoul receives only a handful every year, from North Korean diplomats in Africa or Asia.
Officials are concerned that, if all the loggers are accepted, many more may flee the camps, upsetting relations with Moscow and the tentative peace talks with Pyongyang.
Russian journalists first brought the plight of the North Koreans to light in 1991. The existence of the camps, which first started operating in the 1950s, has been kept secret, and few Russians know about them.
North Korea's official news agency betrayed the government's embarrassment, saying reports of defecting loggers were 'a malicious abuse and slander' and 'an unpardonable insult to the Korean working class, who are masters of the country'.