China on Thursday urged the US to reduce its nuclear arsenal "substantively" and cease proliferation of nuclear materials and technology.

Beijing also called upon Washington to "refrain from extending nuclear deterrence or expanding a nuclear alliance," state media reported.

Wu Qian, a spokesperson for China's Ministry of National Defense, said Beijing "firmly" opposes Washington's "expansion" of its nuclear arsenal and shirking of its nuclear disarmament responsibilities under the pretext of a non-existent "China nuclear threat," Xinhua news agency reported.

Wu said his country pursues a "self-defense nuclear strategy" and maintains its nuclear force at the minimum level required for national security.

"It is common knowledge that the US is in possession of the largest nuclear arsenal in the world, and that it follows a nuclear policy that permits the first use of nuclear weapons," he was quoted as saying the news agency.

In recent years, he said, Washington has "invested heavily in the miniaturization of nuclear weapons for real combat and exercised double standards on nuclear proliferation, which is a severe threat to global strategic stability."