"For us, a nuclear arming of Iran is not acceptable," said Westerwelle. "It is an issue that concerns the entire international community" and not just Israel.

"The security of Israel is not negotiable, particularly for us," he said.

The minister said he favoured negotiations with Iran at this stage but stressed that "the patience of the international community is not endless" and that sanctions remained an option if Iran does not cooperate.

Later, Israeli President Shimon Peres urged Germany to keep the pressure on Iran.

"Threats of destruction, denying the Holocaust, massive funding and supporting terrorist organisations including Hezbollah in Lebanon and Hamas in Gaza, are serious and can't be ignored," Peres said.

Israel, which has the region's sole if undeclared nuclear arsenal, believes Iran's programme is aimed at developing a bomb, a charge denied by Tehran.