SEOUL, South Korea -- North Korea on Tuesday dashed hopes for a quick release of American pilot Bobby Hall, accusing the United States of committing "a deliberate act of espionage."


Hall was taken captive after his U.S. Army OH-58C helicopter strayed into North Korean territory Dec. 17. North Korea says it shot down the chopper, killing Hall's colleague, fellow Chief Warrant Officer David Hilemon. The United States has insisted the aircraft was on an unarmed training mission.


"All facts clearly prove that the intrusion of the U.S. helicopter into the territorial airspace of the DPRK (Democratic People's Republic of Korea) is a grave violation of the sovereignty of the DPRK and a deliberate act for espionage on it," said a statement by the North's official Central Korean News Agency.


"In view of the seriousness of the incident, we cannot but investigate the truth of the incident more deeply."


Jim Coles, a spokesman for the U.S. and UN military presence in Korea, strongly rejected North Korea's accusations. "This absolutely was not a mission of that nature," he said. "As we have said, this was a routine training flight that unfortunately strayed into DPRK airspace."


Washington said it was sending Thomas Hubbard, a State Department official who helped negotiate a nuclear accord that was signed with Pyongyang two months ago, to help negotiate Hall's release.