Vice admiral Kay-Achim Schoenbach made the comments at a think-tank discussion in India on Friday, coming at a sensitive time as Russia has amassed tens of thousands of troops on Ukraine's borders.

Diplomatic efforts are focused on preventing an escalation despite Russia denying it is planning to invade Ukraine.

At the discussion in New Delhi on Friday, Mr Schoenbach said President Putin seeks to be treated as an equal by the West.

"What he (Putin) really wants is respect," he said. "And my God, giving someone respect is low cost, even no cost... It is easy to give him the respect he really demands - and probably also deserves."

Mr Schoenbach conceded Russia's actions in Ukraine needed to be addressed, but he added that "the Crimea peninsula is gone, it will never come back, this is a fact", contradicting the joint Western position that Moscow's annexation of the peninsula from Ukraine in 2014 cannot be accepted and must be reversed.

His remarks, which were published on YouTube and widely circulated on German media, were publicly rejected by the German defence ministry which said Mr Schoenbach's views did not reflect the nation's position in either content or wording.

Read more: What's going on at the Russia-Ukraine border?

Announcing his resignation on Saturday evening, Mr Schoenbach said: "My rash remarks in India... are increasingly putting a strain on my office.

"I consider this step (the resignation) necessary to avert further damage to the German navy, the German forces, and, in particular, the Federal Republic of Germany."

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The Ukrainian Foreign Ministry said in a statement that Mr Schoenbach's comments could impair Western efforts to de-escalate the situation.

Ukraine's Foreign Minister Dmytro Kuleba said separately in a tweet: "Ukraine is grateful to Germany for the support it has already provided since 2014, as well as for the diplomatic efforts to resolve the Russian-Ukrainian armed conflict.

"But Germany's current statements are disappointing and run counter to that support and effort."