Tokyo has some 600 troops based in the southern Iraqi city of Samawah for non-combat humanitarian work, and speculation is high that the soldiers will be withdrawn this year.

But Foreign Minister Taro Aso told reporters it was too soon to discuss a pullout.

"The internal affairs minister and defense minister, who are responsible for security, have not been appointed ... I think negotiations (about Japanese troops) will begin when they are named," Aso told reporters.

In addition, public broadcaster NHK quoted Aso as saying Japan will have to study the Iraqi security situation carefully.

NHK added that Japan would make a decision after consulting with the United States and Britain.

Iraqi Prime Minister Nouri Al-Maliki has said he would make his choice for the two crucial security posts, which were not filled last week along with the rest of his Cabinet because of ethnic and sectarian disagreements.

Al-Maliki says the decision could come as early as Friday, paving the way for their swearing-in on Sunday, when parliament reconvenes.