SEOUL, South Korea — A 24-year-old American who was detained in North Korea this month traveled there alone and left no contact information for his family, according to the New Jersey-based travel company that arranged his trip.

The man, Matthew Todd Miller, was detained by North Korean officials for “rash behavior” at customs at the Pyongyang airport on April 10, the North’s state-run news media said Friday. North Korea accused him of tearing up his tourist visa and demanding asylum.

Uri Tours, which arranged Mr. Miller’s trip, was “informed early on that Mr. Miller had deliberately ripped his visa and had declared that he was ‘not a tourist,’ ” the company’s director, John Dantzler-Wolfe, wrote in an email on Sunday. “Since that time, we have been working with the appropriate diplomatic, governmental and local agencies to resolve the situation.” Uri Tours posted similar information on its website.

Mr. Miller signed up for a private tour, Mr. Dantzler-Wolfe said. As most private tour clients do, he chose to travel with local guides from Uri Tours’ North Korean partner, he said.