Japan has briefed Brazil, Germany and India -- its partners in the "Group of Four" effort to get permanent seats on the U.N. Security Council -- on its latest idea for expanding the council, according to diplomatic sources.

The basic idea would be to enlarge the council membership from the current 15 to 21, the sources said. In their failed bid last year, the four countries sought to become permanent members by submitting a joint resolution to expand the membership to 25.

Japan's new resolution idea, explained to envoys of the other three nations on Friday, calls for increasing both the number of permanent members and "semi-permanent members," the sources said.

Status as a "new permanent member" would be given to countries that win the support of at least two-thirds of the U.N. membership, or 128 countries, but they would not be given veto power.

Other candidate nations would become semi-permanent members with terms longer than two years.

Current nonpermanent members cannot serve more than one term consecutively, but under Japan's plan, semi-permanent members would be allowed to do so.

Of the six new seats, two each would go to Asia and Africa, one to Latin America and one to Europe.

After the Group of Four failed to have its resolution passed by the world body during a General Assembly session that ended in September, Japan had talks with the United States on U.N. reform as Washington was against the G-4's resolution.

The U.S. also apparently has not given full support to Japan's new resolution idea.

Brazil, Germany and India resubmitted the same resolution as last year's early this month without Japan.

The resubmitted resolution calls for adding six permanent and four nonpermanent seats to the council.