PYONGYANG, North Korea—Two American tourists charged with "antistate" crimes in North Korea said Friday they expect to be tried soon and pleaded for help from the U.S. government to secure their release from what they say could be long prison terms.

In their first appearance since being detained more than three months ago, Matthew Todd Miller and Jeffrey Edward Fowle told a local AP Television News crew that they were in good health and were being treated well. They also said they were allowed to take daily walks. The brief meeting was conducted under the condition that the specific location not be disclosed.

Mr. Fowle said he feared his situation will get much worse once he goes on trial.

"The horizon for me is pretty dark," he said. "I don't know what the worst-case scenario would be, but I need help to extricate myself from this situation. I ask the government for help in that regards."

It wasn't clear whether they were speaking on their own initiative, or if their comments were coerced. The TV crew was permitted to ask them questions.

North Korea said the two committed hostile acts which violated their status as tourists. It has said authorities preparing to bring them before a court, but hasn't yet specified what they did that was considered hostile or illegal, or what kind of punishment they might face. The date of the trial hasn't been announced.

Ri Tong II, a North Korean diplomat, declined to answer questions about the Americans at a news conference Friday at the United Nations. But when pressed in a follow-up question he said their cases were "legal issues" and they had "violated our law."

Mr. Fowle arrived in North Korea on April 29. He is suspected of leaving a Bible in a nightclub in the northern port city of Chongjin, but a spokesman for Mr. Fowle's family said the 56-year-old from Miamisburg, Ohio, wasn't on a mission for his church. Mr. Fowle works in a city streets department. He has a wife and three children, ages 9, 10, and 12.

"The window is closing on that process. It will be coming relatively soon, maybe within a month," Mr. Fowle said of his trial. "I'm anxious to get home, I'm sure all of us are."

Mr. Fowle also produced a letter he said he had written summarizing his experience in North Korea.

The attorney for Mr. Fowle's family said Friday his wife hadn't seen the video, but had read news reports about his comments.

"I can tell you that she is very upset, as you can imagine," said attorney Timothy Tepe. He said he and the family were still gathering information and likely would have a statement on Monday.

Less is known about Mr. Miller, or about what specific crime he allegedly committed.

North Korea's state-run media have said the 24-year-old entered the country April 10 with a tourist visa, but tore it up at the airport and shouted that he wanted to seek asylum. A large number of Western tourists visited Pyongyang in April to run in the annual Pyongyang Marathon or attend related events. Mr. Miller came at that time, but tour organizers say he wasn't planning to join the marathon.

"I expect soon I will be going to trial for my crime and be sent to prison," Mr. Miller said. "I have been requesting help from the American government, but have received no reply."

A handwritten note on the front door of his family's home in California asked for privacy.

Neighbor Carol Stewart said Miller first traveled to South Korea about four years ago to visit a brother stationed there with the U.S. Air Force. He found work teaching English and learned Korean, Ms. Stewart said in a July 1 interview. She has since declined to comment out of respect for his parents' wishes.

"He liked it a lot, and he's been there ever since," said Stewart, describing Mr. Miller as the shy one of the four brothers.

North Korea has also been holding another American, Kenneth Bae, since November 2012.

Mr. Bae, a Korean-American missionary who turned 46 on Friday, told a Japan-based pro-North Korean news organization earlier this week that he felt "abandoned" by the U.S. government. He is serving a sentence of 15 years of hard labor for what North Korea has claimed were hostile acts against the state. However, U.S. State Department spokeswoman Marie Harf said Thursday the agency is in regular contact with Mr. Bae's family.

Last summer, authorities moved Mr. Bae from a work camp to a hospital because of failing health and weight loss. He was sent back to the work camp earlier this year, only to be taken again to a hospital less than two months later. His family says he suffers from diabetes, an enlarged heart, liver problems and back pain.

Mr. Bae's sister, Terri Chung, said in a statement Thursday it was the first word the family has had of Mr. Bae since April.

North Korea has in the past waited for senior U.S. officials to come to the country to secure the release of some American detainees. Both Messrs. Fowle and Miller suggested that intervention from the highest levels in Washington—possibly a visit by a former president—might be needed to gain their release.

The U.S. has repeatedly offered to send its envoy for North Korean human-rights issues, Robert King, to Pyongyang to seek a pardon for Mr. Bae and other U.S. detainees with no success.

Washington has no diplomatic ties with North Korea and no embassy in Pyongyang. Instead, the Swedish Embassy takes responsibility for U.S. consular affairs there.

Although a small number of U.S. citizens visit North Korea each year as tourists, the State Department strongly advises against it. After Mr. Miller's detention, Washington updated its travel warning to note that over the past 18 months, "North Korea detained several U.S. citizens who were part of organized tours."

North Korea has been strongly pushing tourism lately in an effort to bring in foreign cash. But despite its efforts to bring in more visitors—mostly from neighboring China—it remains highly sensitive to any actions it considers political and is particularly wary of anything it deems to be Christian proselytizing.

In March, North Korea deported an Australian missionary detained for spreading Christianity in the country after he apologized and requested forgiveness.