Japan has decided to postpone a planned visit to Iraq by Yukio Okamoto, top diplomatic aide to Prime Minister Junichiro Koizumi, due to security concerns, government officials said Friday.

According to officials at the Foreign Ministry, Okamoto's scheduled Saturday departure has been postponed because of instability in northern and southern Iraq.

They also cited Iraq's weak telecommunications infrastructure, which is preventing them from making arrangements with local authorities.

On hearing of the postponement, Koizumi reportedly told Okamoto that he hopes he will go to Iraq as soon as possible, government officials said.

It is unclear when such a visit might take place.

Okamoto was scheduled to go to Baghdad and several other cities to assess which materials -- such as medical supplies -- are in short supply, as well as to study Iraq's reconstruction needs.