Germany's Olaf Scholz said Wednesday that a new Iran nuclear agreement "cannot be postponed any longer", during his first visit as chancellor to Israel, which staunchly opposes efforts to forge a deal with Tehran.

Scholz's visit, which included a ceremony at Jerusalem's Holocaust memorial Yad Vashem accompanied by Israeli Prime Minister Naftali Bennett, comes amid the geopolitical turmoil sparked by Russia's invasion of Ukraine. 

The two heads of government -- both relatively new in office following many years when their countries were ruled by veterans Angela Merkel and Benjamin Netanyahu -- met as rapidly moving world events test their leadership.

Policy differences on Iran, long Israel's arch foe, surfaced at a Jerusalem joint press conference, where Scholz said Berlin "would like to see an agreement reached in Vienna".

The latest round of negotiations to salvage Iran's 2015 nuclear deal started in late November in the Austrian capital and the talks are expected to reach a crunch point in the coming days.

The so-called Joint Comprehensive Plan of Action secured sanctions relief for Iran in return for strict curbs on its nuclear programme to prevent it acquiring an atomic weapon, a goal Iran has always denied pursuing.

"Now is the time to make a decision," Scholz said. "This must not be postponed any longer and cannot be postponed any longer. Now is the time to finally say yes to something that represents a good and reasonable solution." 

The original 2015 agreement unravelled when former US president Donald Trump withdrew from it, with Israeli encouragement. 

Israel's Bennett has said he is "deeply troubled" by the outlines of a new deal taking shape, fearing it does too little to stop Iran from getting the nuclear bomb.

Bennett stressed that Israel is "following the talks in Vienna with concern" and warned that "Israel will know how to defend itself and ensure its security and future".  

Permanent responsibility

At the earlier visit to Yad Vashem, Scholz left a message in the guest book stressing Germany's historical responsibility toward the Jewish state. 

"The mass murder of the Jews was instigated by Germany," he wrote. "Every German government bears permanent responsibility for the security of the state of Israel and the protection of Jewish life."

Bennett said the Holocaust "is the wound that forms the basis of ties between Germany and Israel. From this wound we have built significant and steadfast relations."

When it comes to current events, the two leaders have also diverged on their responses to Russia's war in Ukraine. 

Since the invasion started last week, Scholz's coalition government has reversed a ban on sending weapons into conflict zones and halted the Nord Stream 2 gas pipeline project between Russia and Germany.

He also pledged 100 billion euros ($113 billion) this year to modernise Germany's army and committed to spending more than two percent of Germany's gross domestic product on defence annually, surpassing even NATO's target.

Israel has taken a more conservative approach, citing its warm ties with both Kyiv and Moscow and security cooperation with Russian forces which have a large presence in Syria on Israel's northern border. 

Bennett has resisted Kyiv's request for weapons, according to Israeli media, and this week sent Ukraine 100 tons of non-military assistance, including blankets, water purification kits and medical supplies. 

"We have a very measured and responsible policy whose goal is both to help the Ukrainian people and to do what we can to help alleviate some of the pressures and the consequences of this horrific situation," Bennett said as he stood beside Scholz. 

A short while later, Bennett and Ukrainian President Volodymyr Zelensky held a phone call, their second since the Russian invasion.

Zelensky said in a tweet they spoke about "Russian aggression," while Bennett's office noted that "they agreed to maintain continuous communication".

A Russian attack Tuesday hit Kyiv's Babi Yar, the scene of World War II's biggest slaughter of the city's Jews. Zelensky said later that "it is very important that millions of Jews around the world not remain silent right now". 

Scholz, on a one-day trip, later met Foreign Minister Yair Lapid and visited the Knesset, or Israeli parliament. 

He postponed a scheduled meeting with Palestinian president Mahmud Abbas in Ramallah in the Israeli-occupied West Bank due to the events in Ukraine, the German Foreign Office in Ramallah told AFP.