In the case of Kim Hak-song, authorities said, "A relevant institution is now conducting detailed investigation into his crimes".
Last month, North Korean officials detained Pyongyang University accounting professor Kim Sang Dok.
He worked in agriculture development at an experimental farm at the Pyongyang University of Science and Technology.
"It's my understanding that dialogue between North Korean government officials and USA civilian experts opened today [Monday] in a suburb of Oslo and will continue through tomorrow", a source told the news agency.
DENVER | North Korea denounced Sen. Kim was working toward establishing an organic fermentation fertilizer plant, she added.
Analysts say North Korea often attempts to use foreign detainees to wrest outside concessions, which in the past have sometimes involved high-profile American missions sent to secure the release of detainees.
North Korea says it has detained another USA citizen, accusing him of committing "hostile acts".
China predominantly buys minerals from North Korea, as well as growing amounts of seafood and textiles.
Although Donald Trump tweeted during the campaign that similar detentions would not happen if he became president, Kim Hak-song is the second American to be detained in the largely isolated North Korea since Trump's inauguration.
North Korea claims plot reveals US state-sponsored terrorism
North Korea affirmed the detaining of Tony Kim on Wednesday who was taken from the airport as he was trying to leave North Korea.
The Yalu River Bridge links Sinuiju, in North Korea's North Pyongan province with Dandong, a prefecture-level city in China's Liaoning province, and accounts for more than half of the Pyongyang's trade volume with Beijing.
Kim Hak-song ran projects aimed at improving agricultural yields at Pyongyang University of Science and Technology, David Kim said. A naturalized American citizen who was born in South Korea, Kim Dong Chul is a businessman in his mid-60s who at one time lived in Fairfax, Virginia.
North Korean soldiers march during a parade for the "Day of the Sun" festival on Kim Il Sung Square in Pyongyang, on April 15.
The volunteer faculty of PUST, many of whom are evangelical Christians, has a curriculum that includes subjects once considered taboo in North Korea, such as capitalism. "This is wrong", Lee said.
A State Department official told CNN the United States is "aware of reports" that an American citizen was detained. "When a USA citizen is reported to be detained in North Korea, we work with the Swedish embassy in Pyongyang" to try to secure their freedom. Park declined to comment further.
Just last week, North Korea state media published an 1,800-word report accusing the USA and South Korea of plotting to kill leader Kim Jong Un.
"Life on campus and the teaching at PUST is continuing as normal for the Spring semester".
David Moyes Staying At Sunderland
What that is isn't yet clear, but anything less than £20 million will be met with derision by Sunderland fans. Ellis and the board want me to stay. "But until that time when we are safe, I can't pursue that".