North Korea said Thursday that it has arrested an American for trespassing on its territory from China.

The announcement, made through the state media, KCNA, said the American illegally entered the country on Monday and is undergoing interrogation. Both the State Department and the South Korean government said they do not have any further details regarding the North Korean report.

This week’s arrest marks the second time an American was detained by North Korea within a month. North Korea announced on Dec. 29 that it had arrested an American for illegally crossing into the country from China. The first detained American is widely thought to be Robert Park, a Korean-American missionary who entered the country on Christmas to urge the North Korean Leader Kim Jong-Il to repent and take measures to respect human rights.

According to South Korean activists, Park had crossed the frozen Tumen River Christmas evening carrying a Bible and a letter addressed to Kim Jong-Il.

The letter, a copy of which was posted on the Seoul-based civic group Pax Koreana Web site, reads: “He (God) loves you and wants to save you and all of North Korea today."

“Please open your borders so that we may bring food, provisions, medicine, necessities, and assistance to those who are struggling to survive,” the letter urged. “Please close down all concentration camps and release all political prisoners today, and allow care teams to enter to minister healing to those who have been tortured and traumatized.”

There are about 160,000 political prisoners in prison camps across North Korea, according to South Korean and American government estimates based on testimonies from former prisoners. Among the political prisoners are an estimated 40,000 to 60,000 Christians, according to Open Doors USA.

Open Doors has given North Korea the undesirable title of the world’s worst persecutor of Christians for eight straight years.

The totalitarian regime bans Christianity and has publicly executed citizens found with a Bible.

The United States has said it is working to find out more about Park’s situation, but it has no direct diplomatic relations with North Korea. The Swedish Embassy in Pyongyang looks after Washington’s interest in North Korea and is working on behalf of Washington to find out more information.

Open Doors encourages Christians around the world to join believers inside North Korea to pray for the country’s freedom during several prayer campaigns that are scheduled to take place this year.