As Friday's end to a four-week conference to review the landmark UN treaty aimed at curbing the spread of nuclear weapons neared, delegates failed to reach agreement on a final document.

"To my deep regret, this conference was not able to reach consensus," Gustavo Zlauvinen, president of the 10th Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), told a plenary session at the UN General Assembly.

Zlauvinen had circulated a revised 36-page draft final document, which needed the approval of all 191 countries that are parties to the treaty to be adopted.

The closing plenary meeting to consider the revised draft was delayed while delegates met behind closed doors to try to get all countries on board. As some blamed Russia for blocking the adoption of the final text, Igor Vishnevetsky, deputy director of the Russian Foreign Ministry's Non-Proliferation and Arms Control Department stressed that many countries – not just Russia – didn't agree with "a whole host of issues" in the last draft.

In a statement, Chinese Ambassador for Disarmament Affairs Li Song expressed the Chinese delegation's deep regret that a final document wasn't agreed upon. The ambassador said China endorsed the relevant arrangements proposed by the conference president on the follow-up review process.

China, together with all signatories, will unswervingly commit to maintaining the international nuclear non-proliferation regime with the NPT as its cornerstone, uphold the concept of common, comprehensive, cooperative and sustainable security, and make unremitting efforts to maintain international peace and security and promote NPT’s role in serving peace and development, Li added.

Since the NPT's entry into force in 1970, a review conference has been held every five years to review the implementation of the treaty in nuclear disarmament, nuclear non-proliferation and peaceful use of nuclear energy, and to plan for global governance agenda in the next stage in the field of nuclear energy. 

This year's review conference was originally set for 2020, but was postponed to this year because of the pandemic. The last review conference, in 2015, also ended without an agreement, because of serious differences over establishing a Middle East zone free of weapons of mass destruction.