The International Narcotics Control Board (INCB) said in a report released Wednesday that some of the illegal drugs entering Japan are being traded in North Korean waters, especially amphetamine stimulants, the use of which reached record levels in Japan and the Philippines in 1999.

The report said drug traffickers who bring narcotics into Japan from other countries by boat throw Japanese law enforcement officials off their trail by transferring their illegal payloads to other vessels in North Korean waters.

The INCB urged North Korea and Cambodia to join an international agreement on drug control, naming the two countries as the sole states in East and Southeast Asia that have not signed on as INCB members.

The U.N.-based drug control board expressed concerns at the growing use of amphetamines among Asian youths, saying such drugs are easily accessible in that part of the world.