Ambassador to Myanmar Yuji Miyamoto is trying to confirm the whereabouts of democracy leader Aung San Suu Kyi following revelations by a U.N. envoy that she was being held in a Yangon prison earlier this month, Senior Vice Foreign Minister Tetsuro Yano said Thursday.

"The ambassador is asking the Myanmar government to arrange a meeting with her," Yano told a news conference.

On Wednesday, a senior Foreign Ministry official said Japan will halt fresh economic aid to Myanmar in protest of the military junta's failure to respond to international calls for an immediate release of Suu Kyi.

U.N. special envoy Razali Ismail told Foreign Minister Yoriko Kawaguchi on Wednesday that Suu Kyi was being detained in the prison when he was allowed by the junta to meet her June 10. Razali said he did not know which prison it was, according to Japanese officials.

Yano said Suu Kyi might have been moved since that meeting, because he was told by leaders of the junta earlier this week when he visited Yangon that Suu Kyi is not in a prison.

"They were aware of various reports saying Suu Kyi is in a prison, but they denied that," Yano said.

Suu Kyi and other members of the National League for Democracy have been detained since May 30 following attacks on her entourage in northern Myanmar.

The junta claimed they were detained for their own safety because of violent clashes between NLD supporters and opponents. NLD members have said the attacks were carried out by junta-sponsored mobs.

Yano said the junta should resolve the issue as early as possible so that a friendly relationship between Japan and Myanmar can be maintained.