Japanese media reported on Wednesday that South Korean, U.S. and Japanese satellites detected the delivery of mobile missile launchers to North Korea by sea.

“Chinese companies do not supply North Korea with equipment banned by the relevant resolutions of the UN Security Council,” Chinese foreign ministry spokesman Liu Weimin said.

The spokesman said China “maintains constant dialogue with all sides [in talks] on nuclear non-proliferation in N. Korea and strictly complies with UN laws and regulations.”

In April, Washington accused Chinese company Hubei Sanjiang of selling components used in constructing missile launchers to North Korea.

The accusations came after Western defense experts spotted what appeared to be Chinese-made 16-wheel transporter-erector-launcher (TEL) at a military parade in North Korea to mark the centenary of the birth of its late founding leader Kim Il-sung.

Japan’s Asahi Shimbun said in its report on Wednesday the vehicles were transported on a Cambodia-registered ship Harmony Wish, which arrived in North Korea on August 4, 2011. Japanese coast guard officials later inspected the vehicle and found a document detailing the export of the vehicles.

North Korea, which withdrew from the six-party disarmament talks on its nuclear program three years ago, agreed in February to suspend uranium enrichment, as well as nuclear and long-range missile tests in return for U.S. food aid, opening the way for the restart of negotiations.

However, the UN Security Council tightened its sanctions against N. Korea late in April over the failed ballistic launch, which Pyongyang said was to put a weather satellite into orbit.