July 22, 2009 (DVB), The United States is concerned about possible nuclear ties between Burma and North Korea and reports that North Korea has been supplying material and information on nuclear proliferation to Burma.

The comments were expressed by US Secretary of State Hillary Clinton in Bangkok this morning prior to her visit to the ASEAN Regional Forum (ARF), which begins today on the Thai island of Phuket.

In a television interview Clinton said that the threat of nuclear weaponry was her biggest concern as Secretary of State, Reuters reported.

"So obviously we are very concerned about North Korea and recent reports about perhaps their dealings with what we call Burma," she said.

Fears of strengthening ties between Burma and North Korea will likely feature highly at the ARF, which will be attended by senior officials from 27 countries, including China.

Concerns stem largely from an incident last month in which a North Korean ship being tracked by the US navy on suspicion that it was carrying weaponry appeared to be heading towards Burma, before turning around.

North Korea is under tight UN sanctions following its nuclear test in May that prohibits the export of weapons materials.

Leaked intelligence documents and photographs obtained by DVB also show North Korean officials in Burma advising engineers on the construction of a network of tunnels that could hold heavy weaponry.

The US House of Representatives yesterday approved the renewal of sanctions on Burma, and will now seek approval from the Senate.

Various meetings have been held already this week in the run-up to the ARF. Following the ASEAN Foreign Ministers' Meeting on Monday, a joint communiqué was released calling for the release of political prisoners in Burma as a prerequisite to "free, fair and inclusive" elections.

The statement also addressed the issue of ASEAN's much-criticised policy of non-interference in the internal affairs of Burma, preferring instead to "constructively engage" with the junta.

Reporting by Francis Wade