CANCUN, Mexico - Securing a guarantee for an extension of the Kyoto Protocol is crucial for the nations to move the current climate negotiations forward, said Sergio B. Serra, Brazil's ambassador for climate change during an interview with China Daily on Wednesday.

But countries such as Japan, which are pushing the countries to abandon the Kyoto Protocol, are blocking the progress of the negotiations in Cancun, he added.

"The reluctance of some countries for the second period of the Kyoto Protocol is the biggest stumbling block," said Serra repeatedly during the interview.