The North's leaders fear large-scale starvation will ensue unless the government quickly resumes suspended food rations, the group's newsletter said.
Some in rural areas around the western city of Sariwon and in Pongsan County have also starved to death, the agency said.
With prolonged food shortages following a disastrous harvest and reduced international handouts, grain prices in the North are soaring, threatening the underprivileged, mostly in rural areas.
Rice prices have surged to 3,000 North Korean Won per kilogram, up from 2,000 Won in April, the aid agency said.
A North Korean's average monthly salary is 2,000 to 3,000 Won. One U.S. dollar officially equals 140 North Korean Won. But on the black market $1 buys about 3,000 North Korean Won.
"Many more people will die of hunger within a month if food prices keep going up without relief measures from the state," Han Kyong-Dok, a 56-year-old farmer in Yangdok County, was quoted by Good Friends as saying.
As state food rations have been suspended, many workers are not going to work in order to seek food for their families, despite warnings of strict punishments.
With worsening food conditions, the North has reduced state food rations even to the country's elites in Pyongyang, the country's showcase city, and the core of the Kim Jong-Il regime.
A UN relief agency has appealed for more international food aid for North Korea, saying the impoverished country is 1.66 million tons short of the minimum it needs until this year's fall harvest.
The World Food Program says quick action is needed to avert looming food shortages in the country where millions of people already live on the verge of starvation.
North Korea has depended on international handouts to help feed its 23 million people since the late 1990s, when it was hit by floods and droughts.
