China said on Thursday that it will respect freedom of navigation in the South China Sea but oppose any attempts to challenge its sovereignty in the disputed area as Germany announced plans to send warships to the Indo-Pacific region.

"I want to reiterate that China always upholds a defence policy (that) is defensive in nature," China's Foreign Ministry spokesman Wang Wenbin told a media briefing here.

He was reacting to reports quoting German General Eberhard Zorn's assertion that his country will expand its military presence in the Indo-Pacific along with allies by sending more ships to counter China's enormous build-up.

"China develops necessary military capabilities to defend its legitimate national security interests, which is entirely legitimate and reasonable," Wang said.

"China always respects countries' freedom of navigation and overflight enshrined in international law including the United Nations Convention on the Law of the Sea," he said.

"We firmly reject any country's move to use the freedom of navigation as a pretext to undermine China's sovereignty, endanger China's security and attack and smear China he said.

China claims most of the South China Sea. However, the Philippines, Vietnam, Malaysia, Brunei and Taiwan have counterclaims.