Seoul  - South Korea searched and confiscated four freight containers belonging to North Korea, following United Nations sanctions against the Stalinist state, media reports said Monday.

South Korea's National Intelligence Service ordered the searches of the containers shipped by North Korea on Panama-registered freighter on September 22, when the vessel docked in the southern port city of Busan, the Yonhap news agency said.

No suspicious cargo was found, the report said, quoting port authorities, who said the secret service received tips about hazardous cargo. The ship had arrived from China last month.

Following North Korea's second nuclear test in May, the UN Security Council issued new sanctions against the communist country, which also ask all member states to monitor North Korean shipping for illegal weapons trafficking.

South Korea also joined the US-launched Proliferation Security Initiative, which seeks to counter proliferation. North Korea is a known exporter of illicit weapons. (dpa)