A U.N. panel has found Chinese involvement in more than half of the suspected violations of the North Korean arms and luxury goods embargoes, a Japanese media report said Friday.

A U.N. panel has found Chinese involvement in more than half of the suspected violations of the North Korean arms and luxury goods embargoes, a Japanese media report said Friday.

The panel identified 38 instances in which banned goods have gone to or from North Korea. Of these, 21 have involved China, the Asahi Shimbun reported, citing unnamed sources.

South Korea, Japan and the United States Thursday began a joint naval exercise denounced by North Korea as a "reckless provocation".

Seoul's Defense Ministry said the two-day drill involving destroyers, supply ships and helicopters would practice humanitarian operations such as search and rescue missions. It said no live-fire exercises were planned.

North Korea accused the United States Monday of building up military forces in the region and vowed to strengthen its own defenses "in every way".

The comments came one day after the communist state said it would bolster its nuclear deterrent in the face of what it called U.S. antagonism.

Beijing said Wednesday Chinese companies were not involved in shipping missile launch vehicles to North Korea last year, denying a Japanese newspaper report that accused it of breaking U.N. resolutions.

The Asahi Shimbun report -- based on Japanese government sources -- is the most strident of recent claims that China has been involved in helping to arm its wayward ally Pyongyang.

South Korea's military warned Monday it would immediately retaliate against North Korea's "core command forces" for any attack, after a series of threats from the communist state.

Seoul's armed forces held an unscheduled readiness drill Monday due to a "series of peculiar activities", a defense ministry spokesman said.

North Korea Sunday criticized the arrests of two men in South Korea for allegedly collecting military secrets for Pyongyang and accused Seoul of staging a "fascist crackdown.”

A 74-year-old South Korean man surnamed Lee and another with New Zealand citizenship were arrested in May for allegedly collecting information on army equipment capable of disrupting global positioning system (GPS) signals.

North Korea said Saturday it has no plans "at present" to conduct a nuclear test despite what it called South Korean attempts to provoke the situation.

Seoul's government was trying to aggravate the situation through "uninterrupted provocations" against the North, a foreign ministry spokesman said in a statement carried by Pyongyang's official news agency.

South Korea accused North Korea Friday of "crossing the line" with its recent threats and insults, and pressed the impoverished country to start repayments for past food aid.

The unification ministry, in charge of cross-border affairs, said the North should immediately halt threats and slander against the South's conservative President Lee Myung-Bak.

South Korea's military security chief accused North Korea Thursday of training elite hackers to steal military secrets and stir up public disorder.

"North Korea is trying to steal military secrets and cripple our defense information system by using experts specially trained to hack into our military information network," Defense Security Commander Bae Deuk-Shik told a security forum.