It also signed a pact with China two years ago to jointly develop the zone.
But even longstanding ties with China haven't guaranteed smooth sailing. Earlier this month, a Chinese firm, the Xiyang Group, warned other companies against investing in North Korea, calling its four-year experience trying to tap into North Korea's mining industry "a nightmare."
Xiyang said it invested $37.1 million to set up a joint venture to build a mining facility, and sent 100 workers to North Korea last year. North Korean officials later demanded changes to the contract and when Xiyang refused, they cut off utilities to the plant and deported the workers, Xiyang said in a statement.
On the other hand, the Yatai Group, a Chinese conglomerate, announced last week that it signed a 50-year contract with Rason officials to build a sprawling complex around Unsang Harbor to produce cement and mortar.
The push to develop Rason moves forward, and an AP reporter found Russian crews working this week on renovating rails to link Rajin and the Siberian city of Khasan, which would provide a link to European markets, and laborers upgrading the tracks between Rajin and the Tumen River at the Chinese-North Korean border.
City officials say they are even working on sprucing up tourists sites.
Kim Yong Ho, the president of the Kumyong Co., which provides services to restaurants in Rason, said business in the area is booming and he has seen more customers, both North Korean and foreign.
Associated Press photographer Kim Kwang Hyon in Rason and researcher Flora Ji in Beijing contributed to this report.
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.