North Korea said Tuesday it has detained an American man who illegally entered the country last week, following reports that a missionary from Arizona went to the communist nation on a mission to improve its human rights record.

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American missionary Robert Park is shown in a December 2009 photo released by his parents at the Palomar Korean Church in San Marco, Calif. ((Associated Press))

The North's official Korean Central News Agency said in a brief dispatch that the American was detained and is under investigation after illegally entering through the North Korea-China border last Thursday. It didn't identify the man.

However, the report comes as South Korean activists say American missionary Robert Park, 28, slipped across the frozen Tumen River into North Korea from China last week with letters calling for a change in North Korea's leadership and an end to political prison camps.

The Rev. John Benson, the pastor of Life in Christ Community Church in Park's hometown of Tucson, Ariz., said he was happy to hear Park was alive.

'I pray he comes back in one piece'

"To hear it confirmed is great," Benson said. "I pray he comes back in one piece. That would be the best case scenario."

"He did this to bring awareness to the situation in North Korea, alert the churches around the world to the atrocities and human rights violations. Not pay lip service and do something about it," Benson said. "Drastic situations call for drastic measures."

Jo Sung-rae of the Seoul-based activist group Pax Koreana quoted one of two people who guided Park as saying he heard people who apparently were border guards speaking loudly as soon as Park crossed the border and that he believed the missionary was taken into custody immediately.

Park's detention comes just months after North Korea freed two U.S. journalists who had been arrested in March and sentenced to 12 years of hard labor for trespassing and "hostile acts."