Several of the politicians present were due to travel from Potsdam to Berlin for a meeting of the Quartet on Middle East peace later Wednesday.

US Secretary of State Condoleezza Rice, German Foreign Minister Frank-Walter Steinmeier and Russian Foreign Minister Sergei Lavrov will attend the meeting of the Quartet, which comprises the United States, the UN, the EU and Russia.

The Potsdam meeting was aimed at preparing the summit of leaders of the Group of Eight most industrialized nations in Heiligendamm, northeast Germany, June 6-8.

The ministers were tackling a range of international crises including the Iranian and North Korean nuclear programs, Afghanistan and Kosovo.

But Japan poured cold water on one of the issues Germany had placed at the top of its priority list for the summit -- a binding agreement on reducing greenhouse gases.

Divisions over climate

Foreign ministry spokesman Mitsuo Sakaba said German proposals to complete negotiations on a successor to the Kyoto Protocol on greenhouse gases by 2009 were "premature."

Japan has been leading efforts among Asian nations to limit global warming. It said it believed major emitters of greenhouse gases such as the United States, China and India should agree to join the process before any timetable was put in place.

"Until we know if they will join us, it is premature," Sakaba said.

Germany took advantage of the presence of Rice and Lavrov to hastily convene the Middle East Quartet, the body which drew up the stalled roadmap for peace.

However, faced with the bloodiest internal clashes in Lebanon for decades and the firing of Palestinian rockets into Israel and Israeli airstrikes in Gaza, expectations for the meeting were low.

In Potsdam, the minister said they were troubled by the situation in the region and called on the Palestinian government to put an end to internal strife and missile attacks against Israel, a German delegation source said.

"The spiral of violence must be stopped," Steinmeier told his fellow ministers, the source said.

There was broad agreement that the international community needed to encourage talks between Israeli Prime Minister Ehud Olmert and Palestinian President Mahmoud Abbas.

They urged the Palestinian Authority to fulfill the demands of the Middle East Quartet including renouncing violence, recognizing Israel and respecting previous agreements with the Jewish state.

And they called on Israel to unfreeze Palestinian tax revenue and customs duties.

Kosovo on the agenda

The future status of Kosovo, an issue that bitterly divides Russia and the West, was also on the table in Potsdam.

Russia rejects proposals by chief UN negotiator Martti Ahtisaari to grant Kosovo internationally supervised independence from Serbia.

Steinmeier said he expected a clash over the province at the meeting.

"We are going to have a discussion on Kosovo that will not be easy," he said.

French Foreign Minister Bernard Kouchner, the UN representative for Kosovo from 1999-2001, said the issue was "very difficult."

Russian Foreign Foreign Minister Sergei Lavrov told reporters he wanted "justice" for Kosovo.

The ministers also addressed the situation in strife-torn Afghanistan.

Afghan Foreign Minister Rangeen Dadfar Spanta and his Pakistani counterpart Khurshid Kasuri were attending the Potsdam talks as part of a German-brokered initiative to resolve a dispute about their joint border.

Afghanistan and Pakistan have been trading recriminations about growing violence linked to Taliban extremists on either side of the border.

Steinmeier said cooperation between the neighbors was crucial to regional stability.

"Bringing the two sides together is essential if we want to improve security," he said.