Germany faces charges from Nicaragua at the top UN court on Monday that it is "facilitating the commission of genocide" against Palestinians with its military and political support for Israel.
Nicaragua has hauled Germany before the International Court of Justice (ICJ), demanding judges impose emergency measures to stop Berlin providing Israel with weapons and other assistance.
Germany has hit back at the allegations, with Sebastian Fischer, spokesman for the German foreign ministry, telling reporters ahead of the hearings: "We reject the allegations from Nicaragua."
"Germany has violated neither the Genocide Convention nor international humanitarian law and we will demonstrate this in full before the International Court of Justice," added Fischer.
Nicaragua will set out its case on Monday, with Germany due to respond the following day.
In a 43-page submission to the court, Nicaragua argues that Germany is in breach of the 1948 United Nations Genocide Convention, set up in the wake of the Holocaust.
"By sending military equipment and now defunding UNRWA (UN agency for Palestinian refugees)... Germany is facilitating the commission of genocide," says the submission.
"Germany's failure is all the more reprehensible with respect to Israel given that Germany has a self-proclaimed privileged relationship with it, which would enable it to usefully influence its conduct," added Nicaragua.
Nicaragua asked the ICJ to decide "provisional measures" -- emergency orders imposed while the court considers the broader case.
It is "imperative and urgent" the court orders such measures given that the lives of "hundreds of thousands of people" are at stake, runs the Nicaraguan case.
The ICJ was set up to rule in disputes between nations and has become a key player in the war between Israel and Hamas militants that erupted after the October 7 attacks.
In a separate case, South Africa has accused Israel of perpetrating genocide in the Gaza Strip, charges Israel vehemently denies.
In that case, the court ordered Israel to do everything in its power to prevent genocidal acts and recently toughened its stance, ordering additional measures obliging Israel to step up access to humanitarian aid.
The court's rulings are binding but it lacks an enforcement mechanism -- for example it has ordered Russia to stop its invasion of Ukraine, to no avail.
Nicaragua has requested five provisional measures, including that Germany "immediately suspend its aid to Israel, in particular its military assistance including military equipment."
It also calls on the court to order Germany to "reverse its decision to suspend the funding of UNRWA."
Germany said in January it was halting funding pending a probe into Israeli accusations that several UNRWA staff members took part in the October 7 assault.
Nicaragua said in its submission that "it could be comprehensible" that Germany would support an "appropriate reaction" by ally Israel to the October Hamas attacks.
"But this cannot be an excuse for acting in violation of international law," said Nicaragua.
On Friday, German Foreign Minister Annalena Baerbock said that Israel had "no more excuse" to delay aid getting into Gaza.
The bloodiest-ever Gaza war began with Hamas's unprecedented October 7 attack on Israel that resulted in the deaths of 1,170 Israelis and foreigners, most of them civilians, according to an AFP tally based on official Israeli figures.
Palestinian militants also took around 250 hostages, about 130 of whom remain in Gaza, including 34 the army says are dead.
Israel's retaliatory campaign has killed at least 33,175 people, according to the health ministry in Hamas-run Gaza, while the United Nations has warned of "catastrophic" hunger.
