U.S. diplomatic cables released by WikiLeaks to London's Guardian newspaper quote a Myanmar source as saying North Korea was building a secret nuclear site in the foothills west of Rangoon.
"The North Koreans, aided by Myanmar workers, are constructing a concrete-reinforced underground facility that is '500ft from the top of the cave to the top of the hill above'," the cable reads.
Myanmar was suspected as far back as 2002 of wanting to develop a nuclear weapon with North Korea's help, the Guardian adds. U.S. diplomatic cables from 2004 cite "alleged" North Korean involvement in underground facilities in the isolated Central Asian country.
One source mentioned in the cables said surface-to-air missiles were allegedly under construction in the remote jungles of Myanmar. Dock workers also reported seeing "suspicious" cargo, the British newspaper adds.
Authorities in Myanmar, the Guardian reported, deny the claims, saying there are no North Koreans in the country.