Achim Steiner, a UN under-secretary general who is director of the UN Environment Programme (UNEP), told the China Daily the extra round of negotiations would take place in the north Chinese port city of Tianjin, which is close to Beijing.
"China will introduce some new ideas and opportunities to move the negotiations forward," said Steiner, who has been visiting China.
Governments are hoping to strike agreement on a new binding climate change treaty after a summit in Copenhagen late last year ended with a weak and non-binding accord.
The newly-added Tianjin talks will come in the build-up to the next major ministerial meeting in Cancún, Mexico, from 29 November to 10 December, when climate officials hope to agree on the key elements of a new treaty, if not the details.
China is the world's biggest emitter of greenhouse gases from human activities, having outpaced the United States, and its position on controlling emissions will be crucial in efforts to build a new pact on fighting global warming.
But officials from China and other countries have voiced doubts that Cancún can clinch a binding climate treaty. That was more likely to occur during major climate talks in South Africa at the end of 2011.
In May, Xie Zhenhua, who led China's delegation to the stormy negotiations in Copenhagen, said the only target for the gathering in Cancún was a "positive result."
"We are having talks in order to see if we could have some kind of messages that can be channelled into the formal negotiations, for instance on MRV (monitoring, reporting and verification)," said EU Climate Action Commissioner Connie Hedegaard after a meeting of the Major Economies Forum on energy and climate (MEF), taking place in Rome on 1 July.
Speaking to EurActiv at the European Business Summit last week (1 July), she predicted that negotiations would be tough without progress on MRV.
"I see some progress. The Indians for instance are coming up with different ideas, trying to be very constructive, trying to see where ends meet," Hedegaard said, adding that Europe would like to move from talking generalities to looking at the details of what the new system would look like.
"If we cannot progress on MRV, then I think it is going to be difficult," she said.
(EurActiv with Reuters.)