Aijalon Mahli Gomes acknowledged his wrongdoing during a trial at the Central Court Tuesday, the North's official Korean Central News Agency said in a brief dispatch.
The North said last month that it arrested Gomes, 30, of Boston on Jan. 25 for trespassing after he crossed into the country from China. He was the fourth American to be detained in communist North Korea on charges of illegal entry in little over a year.
Gomes, a graduate of Bowdoin College in Maine, had been teaching English in South Korea and no details have emerged about why he went to the North. However, a Seoul-based activist - Jo Sung-rae - said Gomes may have been inspired by his acquaintance with an American missionary who made a similar trip to the North in December to protest the country's human rights record.
The KCNA report said the court sentenced Gomes to eight years of "hard labor" and a fine of 70 million won. North Korea's official exchange rate is 100 won to the dollar.
"An examination was made of the hostile act committed against the Korean nation and the trespassing on the border of (North Korea) against which an indictment was brought in and his guilt was confirmed" according to the country's criminal code, it said.
Analysts say verdicts issued by the Central Court - North Korea's highest - are final and cannot be appealed.
But Yoo Ho-yeol, a North Korea expert at Seoul's Korea University, said Gomes would eventually be released as the North appears to want to use his case as a bargaining chip in negotiations with the U.S. on its nuclear program.
"Continuing to hold him in custody is also a burden for North Korea" as it will only galvanize criticism of its human rights record, Yoo said.
The North is under international pressure to return to stalled nuclear disarmament talks it quit last year.
Representatives of the Swedish Embassy in North Korea, which looks after U.S. interests in the country, witnessed the trial, the KCNA report said. A person who answered the telephone of the first secretary at the Swedish Embassy in Pyongyang referred queries to the U.S. State Department.
In Washington, State Department spokeswoman Joanne Moore said the government has seen reports about the matter, but that she could not immediately comment.
Thaleia Schlesinger, spokeswoman for Gomes' relatives, said they are "disturbed" by the verdict and will pray for his early return.
"The family has no comment beyond that they are praying for him and hoping for his return home as soon as possible," Schlesinger said. "Needless to say, they are disturbed (by the sentence) but they are hopeful that he would be returned home to them and they are praying for that."
Three other American citizens have been arrested after crossing into North Korea over the past 13 months.
Missionary Robert Park strode into North Korea from China on Christmas Day in a self-proclaimed mission to draw attention to North Korea's human rights record and to call for leader Kim Jong Il to step down. He was released in February after more than 40 days in custody.
Two American journalists, Laura Ling and Euna Lee, were arrested in March last year near the Chinese border and sentenced to 12 years of hard labor for illegal entry and engaging in hostile acts. They were freed in August after former U.S. President Bill Clinton made a high-profile humanitarian visit to Pyongyang to negotiate their release.
U.S. officials have said they want to make sure that Gomes is returned to the United States as soon as possible.