Ban, visiting Tokyo at the invitation of Japan, was due to meet Foreign Minister Hirofumi Nakasone later in the day, before he visits Prime Minister Taro Aso and Japan’s opposition leader Yukio Hatoyama on Wednesday.

His planned visit to Myanmar on Friday and Saturday comes amid the internationally-condemned trial of the Nobel prize winning democracy leader.

Ban’s trip to Asia also coincided with reports that a North Korean ship carrying weapons and related parts was headed to Myanmar.

Worries over proliferation intensified in Japan as Japanese police arrested three businessmen Monday for allegedly trying to export a device that can be used to develop weapons of mass destruction to Myanmar on Pyongyang’s orders.

Japan, which has taken a hardline stance against North Korea, historically maintained relatively friendly relations with Myanmar, the country formerly called Burma, and was previously its leading donor.

Tokyo drastically reduced development aid to Myanmar over human rights concerns, particularly after the junta cracked down on pro-democracy demonstrations led by Buddhist monks in 2007.

However, the Japanese government refused to join its Western allies in imposing sanctions on Myanmar.

Myanmar and hardline communist North Korea, both of which are severely criticised internationally for their human rights abuses, restored diplomatic relations in 2007 after a 24-year rift.

Tensions in Asia have soared since North Korea’s long-range rocket launch in early April and its second nuclear test in May. Pyongyang later warned that “dark clouds of nuclear war” are gathering over the peninsula.