This is a move that could further stoke tensions with the United States.
Kenneth Bae, 44, was in a group of five tourists who visited the northeastern city of Rajin on a five-day trip last November and has been held by police since then.
KCNA, the North's official news agency, said Bae entered the North on November 3.
"In the process of investigation he admitted that he committed crimes aimed to topple the DPRK with hostility toward it," the KCNA report said, using the North's official title of the Democratic People's Republic of Korea.
"His crimes were proved by evidence," it said, adding he would soon be taken to the Supreme Court "to face judgment".
Spiralling tensions
Former UN ambassador Bill Richardson delivered a letter regarding Bae to officials during a trip to North Korea in January, although he was unable to meet Bae.
Richardson has made numerous trips to North Korea that have included efforts to free detained Americans.
Tensions between North Korea and South Korea and Seoul's ally the United States have spiralled in recent weeks since the United Nations tightened sanctions after the North's third nuclear weapon test in February.
The toughening of those sanctions led to a dramatic intensification of North Korea's threats of nuclear strikes against South Korea and the United States.
On Friday, Pyongyang rejected a call for formal talks to end a standoff that led operations at a joint industrial complex shared by the North and South to be halted.
South Korea in turn said it would pull out all its remaining workers from the Kaesong factory complex, which is just inside North Korea and is one of the North's few sources of ready cash. – Reuters