UPDATE 1-German Leopard 2 tanks have reached Ukraine -security source

(Adds confirmation from security source, details)

BERLIN, March 27 (Reuters) - The 18 Leopard 2 battle tanks pledged by Germany to support Ukraine in its war against Russia have arrived in Ukraine, a security source said on Monday, confirming a report by Spiegel news magazine.

Germany agreed in January to supply the tanks, regarded as among the best in the West's arsenal, overcoming misgivings about sending heavy weaponry that Kyiv says is crucial to defeat Russia's invasion but Moscow casts as a dangerous provocation.

Besides the 18 main battle tanks, 40 German Marder infantry fighting vehicles, and two armoured recovery vehicles had also reached Ukraine, the security source said.

The German army trained the Ukrainian tank crews as well as the troops assigned to operate the Marder vehicles for several weeks on training grounds in Muenster and Bergen in northern Germany.

Beyond the German vehicles, three Leopard tanks donated by Portugal also reached Ukraine, according to the security source.

(Reporting by Sabine Siebold and Rachel More, Editing by Friederike Heine and Tomasz Janowski)