Missile components companies in Russia and Uzbekistan are cooperating in the sales of parts to Stalinist North Korea, which has pledged to the US it will stick to a moratorium on missile testing, the Washington Times reported.

Parts being sold included the aluminium alloys, laser gyroscopes and missile guidance systems, the report said, adding that the information was contained in a sensitive intelligence reports sent to senior policymakers.

The report also said Russia was collaborating with a North Korean missile company to send Scud missiles to Yemen.

US officials are due to meet North Korean counterparts in Kuala Lumpur next month for a new round of talks on Pyongyang's missile program and alleged proliferation activities.

President Bill Clinton warned on Thursday that despite signs of reconciliation that emerged from a summit this month between North Korea and South Korea, Pyongyang's weapons program remained a threat.

The report also quoted a National Security Agency assessment on June 8, which found that Russia had exported tritium gas to a nuclear weapons research centre in Iran.

Tritium is sometimes used to enhance the explosive power of nuclear warheads.

"The North Koreans suggested Kuala Lumpur and it was fine with us," an embassy spokesman said. "The Malaysians are gracious hosts and it works well."

He was referring to an earlier meeting between the US and North Korea at a hotel in the city on the subject of US servicemen missing since the Korean War.

After three days of talks early this month an agreement was reached to allow specialists to resume the search for remains.

The missile talks will be held between July 10 and 12 and cover a wide range of concerns including North Korea's alleged missile exports, the US State Department said.

US and North Korean negotiators have held four rounds of missile talks since 1996, but talks have have been suspended for 15 months.