The Iranian foreign minister was to arrive in Japan late Wednesday aboard a specially-chartered plane ahead of talks Thursday with Prime Minister Junichiro Koizumi and Kawaguchi. He was to depart Japan Friday.
Kawaguchi told reporters Wednesday that Iran's dealings with the International Atomic Energy Agency would not hinder negotiations on the multibillion-dollar deal to develop a massive oil field in Iran, regardless of the nuclear issue.
"These are two separate policy goals. We have not come to the point where we need to discuss these together," she said. "Each one is important."
She said, however, that she will urge Iran to sign the "additional protocol" to the nuclear Non-Proliferation Treaty (NPT) to allow snap UN inspections of Iran's nuclear sites.
"Japan shares the international community's nuclear weapons concern. We are glad that the IAEA is there talking with the Iranians," she told a press briefing.
"We have been pressing Iran that it is very important for them to sign and implement the additional protocol."
Kawaguchi noted that 99 percent of Japan's oil comes from outside sources.
"Therefore, securing oil has been a very important policy goal for Japan," she said.
Visiting Iranian nuclear energy officials said Tuesday there were positive discussions on the additional protocol.
During a bilateral working-level meeting held here, Iranian officials also reiterated their right to peaceful use of nuclear materials.
Tehran is under strong international pressure to sign the extra NPT clause to prove it is not secretly developing atomic weapons, with the United States accusing Iran of using its atomic energy program as a cover for nuclear weapons development.