A mass exodus of North Korean workers from the Far East of Russia is under way, according to reports coming out of the region.

As the two Koreas edged towards the brink of war this week, it appears that the workers in Russia have been called back to aid potential military operations.

Vladnews agency, based in Vladivostok, reported that North Korean workers had left the town of Nakhodka en masse shortly after the escalation of tension on the Korean peninsula earlier this week. "Traders have left the kiosks and markets, workers have abandoned building sites, and North Korean secret service employees working in the region have joined them and left," the agency reported.

Russia's migration service said that there were over 20,000 North Koreans in Russia at the beginning of 2010, of which the vast majority worked in construction. The workers are usually chaperoned by agents from Kim Jong-il's security services and have little contact with the world around them. Defectors have suggested that the labourers work 13-hour days and that most of their pay is sent back to the government in Pyongyang. Hundreds of workers have fled the harsh conditions and live in hiding in Russia, constantly in fear of being deported back to North Korea.

"North Korea's government sends thousands of its citizens to Russia to earn money, most of which is funnelled through government accounts," says Simon Ostrovsky, a journalist who discovered secret North Korean logging camps in the northern Siberian taiga. "Workers are often sent to remote locations for years at a time to work long hours and get as little as three days off per year." Now it appears that some kind of centralised order has been given for the workers to return home.

Russia's Pacific port of Vladivostok is thousands of miles and seven time zones from Moscow, but only around 100 miles from the country's heavily controlled border with North Korea. In 1996, a diplomat from the South Korean consulate in the city was murdered with a poisoned pencil, in what was widely believed to be a hit carried out by the North's secret agents. There are even two North Korean restaurants in the city. It is not known how many of the workers in other Russian towns have been called back to their homeland this week, or whether the exodus is permanent or temporary.