SEOUL, Oct 7 (Reuters) - COVID-19 aid supplies have arrived in North Korea but are being held in quarantine in its seaport of Nampho, the World Health Organization (WHO) said on Thursday, as the isolated nation shows few signs of easing strict border lockdowns. North Korea sealed its borders when the coronavirus pandemic began last year, though officials in neighbouring South Korea and the United States have cast doubts on its claim to have never had a case, despite a lack of signs of major outbreaks. In its latest weekly report for South and East Asia, covering the period to the end of September, the WHO said it had begun shipments through China"s port city of Dalian, near the border with North Korea. "To support DPR Korea with essential COVID-19 medical supplies, WHO started the shipment through Dalian port, China for strategic stockpiling and further dispatch," the agency said, using an abbreviation of the North"s official name. The aid in quarantine in the North includes emergency health kits, medicines and medical supplies for essential health services, said Edwin Salvador, the WHO representative to North Korea. "We are informed that these items, along with others from other U.N. agencies, remain under quarantine at the seaport," he said in a statement to Reuters. The supplies went by ship to the North"s port city of Nampho after its public health ministry told U.N. agencies a few months ago that some aid stranded in China would be let through Dalian"s port. "Consequently, WHO was able to transport some of the items by ship to Nampho seaport," Salvador added.By Sept. 23 North Korea had tested at least 40,700 people for the coronavirus with no positive results, the WHO has said. Chinese customs data show that maritime shipping routes between North Korea and China appear to be opening, but signs of goods movement between them via land have not been detected, an official of South Korea"s unification ministry, which handles relations with the North, told the Yonhap news agency. (This story corrects to insert dropped word "ago" in paragraph 7)