UNITED NATIONS, Dec. 17 (Xinhua) -- The international community should not give up on climate talks although the latest United Nations (UN) Climate Change Conference (COP25) ended with no deal on key issues, officials have said.

The COP25 came to an end on Sunday after an unprecedentedly long extension, yet negotiators failed to reach an agreement on Article 6 of 2015 Paris Agreement about the details of carbon market mechanisms.

The negotiations were scheduled to end on Friday but continued throughout Saturday and into Sunday morning. With over 40 hours of extension, it was the longest COP in history, which was quite usual to be extended due to intense discussions.

In a statement released Sunday on the UN website, UN Secretary-General Antonio Guterres said that he was "disappointed" at the results of the COP25.

"The international community lost an important opportunity to show increased ambition on mitigation, adaptation and finance to tackle the climate crisis," said Guterres.

"But we must not give up and I will not give up," he said.

"I am more determined than ever to work for 2020 to be the year in which all countries commit to what science tells us is necessary to reach carbon neutrality in 2050 and a no more than 1.5 degree temperature rise," he said.

Speaking at a press conference in New York on Monday, Stephane Dujarric, spokesperson for Guterres, said the UN will not consider giving up on the Paris Agreement or any other deals already reached.

The Paris Agreement is clear in its scope. The problem behind the outcome of this year's COP25 is that the negotiators were unable to reach a consensus, he said.

Carolina Schmidt, chairwoman of the COP25 and the environment minister of Chile, said Sunday that the meeting was not a complete loss and some "concrete progress" overall had been made.

At a press briefing on Monday, China's Foreign Ministry spokesperson Geng Shuang said China regretted that negotiators failed to reach an agreement on core issues.

"To deal with climate change, the urgent task is to uphold multilateralism," Geng said, "and to implement the Paris Agreement on the basis of equity and in accordance with all parties' common but differentiated responsibilities and respective capabilities."

Geng said China would continue to push for the implementation of the Paris Agreement, improve the global climate governance system so that it is fair, equitable and mutually beneficial, and contribute to building a community with a shared future for humankind.