Germany has criticised Italy for opposing its campaign for a permanent seat on the UN Security Council.
Many feel the structure of the security council is outdated
German Foreign Minister Joschka Fischer said Europe would lose out if it was the only region not to have a new representative on an enlarged council.
Under a proposed reform, Germany, Brazil, India and Japan are seeking additional permanent seats for themselves and one African nation.
Permanent members France and Britain back the plan, but Italy opposes it.
The drive to reform the council was launched by United Nations Secretary General Kofi Annan, after its failure to reach agreement over Iraq last year.
Brazil, Germany, India, and Japan this week called for new permanent seats for themselves and Africa, saying the plan would boost the legitimacy of the UN.
But Italy voiced its opposition, saying it favoured only the inclusion of more non-permanent seats.
"We do not believe the council's difficulties can be resolved through new permanent, irrevocable appointments," Foreign Minister Franco Frattini said, adding that Arab nations might feel excluded.
Mr Fisher said he regretted Rome's position, in an interview published by Italy's Corriere della Sera newspaper on Saturday.
"Following the criteria accepted by everyone, the other regional groups, overcoming divisions and difficulties, will have a new representative on the expanded council. We Europeans won't," he said.
Mr Fischer added that it was illogical for Italy to reject German candidacy without applying itself.
India, Japan, Brazil, and Germany want permanent seats
He urged the Italians to seek a permanent seat in "a true competition between two countries that are friends and allies".
Reform of the security council has sparked intense debate at the UN.
Senegal called for two permanent and two non-permanent African seats, while Nigeria argued it was qualified for permanent membership.
Washington, meanwhile, has backed Japan's bid for a permanent seat, but reserves judgement on Germany, India and Brazil.
Britain, China, France, Russia, and the US have been permanent members with the power of veto since the council was formed after World War II.
The 10 other council members are chosen for two-year terms by regional groups.