The autonomous underwater vehicle, developed by Israeli company IAI together with German submarine- and warship-maker TKMS, was received in the northern port of Eckernfoerde, the navy said in a statement.

The army on its website said the Blue Whale was the navy's "largest and most advanced unmanned underwater vehicle to date".

The device was tested in the Baltic Sea, a flashpoint for tensions between Russia and NATO since Moscow's 2022 invasion of Ukraine, the army said.

Military experts and European leaders say Russia has ramped up its "hybrid war" in the strategic region -- now bordered entirely by NATO members, with the exception of Russia -- through airspace incursions and suspected sabotage of undersea cables.

TKMS said the Blue Whale was capable of "conducting reconnaissance operations, detecting targets above and below the sea surface, collecting acoustic information, and locating sea mines on the seabed".

Israel and Germany have upped their defence cooperation in recent months and in January signed a security pact to expand joint work on counterterrorism and cyber defence.

In December, Germany approved a $3.1 billion expansion of a contract for the Arrow 3 anti-ballistic missile defence system, which is Israeli-made and developed with US support.