The 30 experts and officials, who include Sergio de Queiroz Duarte, the chair of the New York meeting, will hold two days of talks behind closed doors in Tokyo.

The New York conference will review progress on the Nuclear Nonproliferation Treaty, which Japan has championed as it is the only country to have suffered nuclear attack and is in a heated row with nuclear aspirant North Korea.

UN atomic energy chief Mohamed ElBaradei has proposed that the New York meeting discuss a five-year international moratorium on building facilities for uranium enrichment and nuclear reprocessing so weapons states could lead by example.