Prime Minister Shinzo Abe has urged Iranian President Hasan Rouhani to resolve Tehran's alleged nuclear weapons program with flexibility and by building on a recent shift toward dialogue, a Japanese official said.

Abe told Rouhani on Thursday that "showing flexibility should be a key" to settling the matter of Iran's nuclear development and that Tokyo is ready to assist. He also welcomed Rouhani's recently stated intention to increase dialogue with the international community and advised him not to pass up the current chance for progress on the issue.

"The window of opportunity will not remain open forever," Abe was quoted as telling Rouhani, who only took office in August, during their talks on the sidelines of the U.N. General Assembly in New York.