UNITED NATIONS - UN chief Ban Ki-moon said Wednesday he had launched an initiative to secure the release of two US journalists detained in North Korea but would not disclose details.

"I have taken my own initiative even though I am not able to disclose (details)," he told reporters here.

He said he had appealed to Pyongyang to release Euna Lee and Laura Ling "on humanitarian grounds" but would not elaborate.

North Korean border guards detained the two US TV reporters on March 17 along the frontier with China while they were researching a story about the plight of refugees fleeing the North.

Last June, a North Korean court sentenced Ling, 32, and Lee, 36, to 12 years of "reform through labor" for an illegal border crossing and an unspecified "grave crime."