Germany sent two warships to the Indo-Pacific region on Tuesday in a bid to strengthen its military presence in the region amid rising tensions between China and Taiwan and over the disputed South China Sea.

Those tensions were putting pressure on the freedom of navigation and free passage on trade routes, Defence Minister Boris Pistorius said at the northern German navy base in Wilhelmshaven.

Some 40% of Europe's foreign trade flows through the South China Sea. "Looking the other way, showing no presence in the Indo-Pacific in support of the international rules-based order, that's not an option for Germany," he told reporters before the vessels departed. "Presence matters."

Beijing claims almost the entire South China Sea as its own, despite an international tribunal ruling that Beijing has no legal basis for these claims. China also claims democratically-governed Taiwan as its own territory, despite the latter's strong objections.

The supply ship Frankfurt am Main set sail from Wilhelmshaven, while the frigate Baden-Wuerttemberg left from the Spanish harbour of Rota. The vessels will meet at sea, then sail to Halifax in Canada and onwards to the Indo-Pacific.

The ships will pass through the South China Sea but it was not clear whether they will also sail through the Taiwan Strait as the United States has done, a move certain to irk Germany's top trade partner, China.

"Since several allied navy vessels have passed (the Taiwan Strait), this obviously is an option. But no decision has been taken yet," said Pistorius.

In 2021, a German warship sailed into the South China Sea for the first time in almost 20 years, joining other Western nations in expanding military presence in the region amid alarm over China's territorial ambitions.