BEIJING, May 7 -- China on Wednesday welcomed a protocol to a nuclear-free treaty which assures five Central Asian nations that nuclear weapons won't be used against them.

"It is a major event in the process of nuclear-weapon-free zones establishment," Chinese Foreign Ministry spokeswoman Hua Chunying said.

The Treaty on a Nuclear-Free Zone in Central Asia, which came into force in 2009, commits its signatories -- Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan -- to refrain from developing, acquiring or possessing nuclear weapons.

On Tuesday morning, China, France, Russia, the United Kingdom and the United States signed a protocol with the five countries at UN headquarters pledging not to use or threaten to use nuclear weapons or other nuclear explosive devices against any party to the Treaty. Liu Jieyi, China's permanent representative to the United Nations, signed the protocol on behalf of the Chinese government.

Hua said China actively practices "amity, sincerity, mutual benefit and inclusiveness", and commits itself to maintaining regional peace and stability, while positively advancing security cooperation with neighbors.

China is committed to no first use of nuclear weapons at any time or in any circumstances, and promised under no circumstances will it use or threaten to use nuclear weapons against non-nuclear-weapon states and nuclear-weapon-free zones.

"The five Central Asian countries are all friendly neighbors of China," Hua said.

Hua said the Chinese side appreciated Kazakhstan for playing a leading role in the process of the protocol. "China will also continue to actively support international efforts to establish nuclear-weapon-free zones in the Middle East, Southeast Asia and other regions," Liu added.