BERLIN - Israel's Cabinet convened Monday for the first time in Berlin, the former heart of the Nazi regime, for a special joint session with the German government highlighting the two nations' strong bond six decades after the Holocaust.

Germany's efforts to curb Iran's nuclear ambitions figured high on the agenda, and Chancellor Angela Merkel said her country would back tougher new sanctions against Iran if that country did not change its tune on its nuclear program.

"If Iran's reactions don't change, we will help work on comprehensive sanctions," Merkel said.

Germany has long been part of the group of nations seeking to address concerns over Iran's nuclear ambitions, which Israel and most of the West believes is meant to develop an atomic bomb. Israel considers a nuclear Iran to be an existential threat and has hinted at attacking Iran if international diplomacy fails.

Israeli Prime Minister Benjamin Netanyahu also pressed hard for sanctions, saying the time has come to confront Iran's Islamic regime.

"The true face of this regime has been unmasked in the year that has just passed ... and we know from recent history that a regime that tyrannizes its own people will tyrannize the world," he said at a joint press conference with Merkel. "If we don't apply sanctions, crippling sanctions, against this Iranian tyranny, when shall we apply them? If not now, when?"

A high-ranking Israeli defence official, speaking on condition of anonymity because the talks are in early stages, said Jerusalem has also recently begun discussing the possibility of acquiring a sixth submarine built by Germany. It already has three, and two others are under construction. Israel is also interested in German-made Meko-a 100 warships. Israeli officials were expected to ask about purchasing technology used on these ships. Israel would then manufacture its own ship with the technology, the official said.

Environmental issues, economic co-operation and efforts to restart the Middle East peace process were also discussed during the one-day visit by Israeli Netanyahu and six of his ministers -- including his defence and foreign ministers.

The trip was originally scheduled for late November, but was put off at the last moment when Netanyahu fell ill with a viral infection and a light fever.

The Cabinet meeting came after a joint visit to Berlin's Holocaust memorial, which consists of a field of 2,711 grey slabs that serve as a tribute to the Holocaust's 6 million Jewish victims.

Netanyahu signed the memorial's guest book with thanks for the "invaluable preservation of the Holocaust."

Israel was established three years after the end of the Second World War. Since then, Germany has paid US$39.4 billion in compensation to Holocaust survivors in Israel, some 250,000 of whom are still alive.

Some Israelis still refuse to buy German-made goods or visit Germany.

But since the two countries established diplomatic ties in 1965, Germany has become perhaps Israel's strongest ally in Europe.

In his comments, Netanyahu thanked Germany for its commitment to Israel.

"Germany faces, without flinching for a second, the darkest chapters of its past it order to build a brighter future for its people and for the world," he said. "It is something we deeply appreciate, something that has momentous historic significance."

Before visiting the memorial, the two nations signed an agreement to provide assistance to developing nations, particularly in Africa, in the fields of desert agriculture and water management.

Germany is Israel's third-largest trade partner after the U.S. and China.

Monday's session follows a historic visit in March 2008 by German Chancellor Angela Merkel and her Cabinet to mark the 60th anniversary of Israel's independence. During that three-day visit, Merkel addressed the Israeli parliament, in German, and expressed shame over the Holocaust. The 20-minute speech earned Merkel a standing ovation.

Israeli and German governments are to hold joint Cabinet sessions once a year in future. Germany has such arrangements with five other nations.

Germany, like other European nations, has little influence on Israeli-Palestinian peacemaking -- that's a role largely reserved for the U.S. -- but has contributed hundreds of millions of dollars in aid to the Palestinians over the past decade.