State news agency KCNA said the man, whom it named as Bruce Byron Lowrance, had told officials he was "under the command" of US spy agency the CIA.
A man of the same name was deported from South Korea in November 2017 after being found wandering near the highly fortified border with the North.
There has been no official confirmation of the man's identity.
"While being questioned, he said he had illegally entered the country under the command of the US Central Intelligence Agency," KCNA reported.
"Relevant authorities have decided to expel him from the country."
US authorities have not yet commented on the report.
Last year, US media said the man expelled from South Korea - who has also been named as Lawrence Bruce Byron - had claimed he wanted to help resolve tensions between North Korea and the US.
He is originally from Michigan, the Los Angeles Times reported, and was arrested in a restricted area near the border with the North in Yeoncheon county, about 40 miles (64km) north of the capital Seoul.
North Korea released three US detainees in May ahead of a summit between its leader Kim Jong-un and US President Donald Trump in Singapore.
In 2017, the North released a US student who had been arrested a year earlier for stealing a propaganda sign.
Otto Warmbier was returned to the US in a comatose state and later died, worsening tensions between the two countries.
His parents say his death was the consequence of torture but North Korea says he contracted botulism during detention.