Negotiators and non-governmental organizations attending the Cancun climate change conference slammed Japan Wednesday for its "unconstructive" stance on the Kyoto Protocol.

Japan's opposition to extending the Kyoto Protocol -- the binding international treaty that commits most of the world's developed countries to making emission cuts, is not very constructive, Brazilian Ambassador for Climate Change Sergio Serra told Xinhua.

Its stance on this issue "obviously will" be an obstacle to the Cancun conference "unless Japan compromises a little bit," Serra said.

"There is no way to move forward if we don't have the continuation of the Kyoto Protocol," Serra added.

Japan's opposition was made by Jun Arima, deputy director-general for environmental affairs at Japan's Ministry of Economy, Trade and Industry,

"Japan will not inscribe its target under the Kyoto Protocol on any conditions or under any circumstances," he said late Tuesday in an open session.

Serra said it's "ironic" that Japan, home country of the Kyoto Protocol, wants to throw it away.

Although the first commitment period of the Protocol will expire in 2012, Serra said "The Kyoto Protocol itself has no expiration date."

Su Wei, chief Chinese negotiator and head of the climate change department of China's National Development and Reform Commission, told reporters that he noticed Japan's strong opposition to the second commitment period of the Protocol.

According to Su, Japan's stance has triggered a strong response from negotiators and will greatly affect the balanced outcome of the conference.

Su deemed the Protocol as a key issue to a climate regime and a basis of international framework to address global warming.

"It is one of the crucial issues concerning the success of the Cancun conference," he said.

The Kyoto Protocol was adopted in Japan in 1992 by major emitting countries, who committed themselves to cutting greenhouse gas emissions by 5.2 percent from their 1990 baseline levels by 2012.

However, the U.S. congress refused to ratify the Protocol.

The world's non-governmental organizations also condemned the Japanese government's rhetoric as threatening to severely undermine the environmental integrity of the global response to climate change.

"That my government is now trying to destroy this treaty that bears a Japanese name is a disgrace. The Japanese government's shameful comments in Cancun signal that it cares more about big business than mother earth," Mayuko Yanai of Friends of the Earth Japan told a press conference.

"The government claims it believes most Japanese people support this position. This misunderstanding makes dangerous climate change all the more likely," he said.

Mohamed Adow, senior climate change advisor of Christian Aid, believed that Japan's hardline opposition to the Protocol "puts the global climate architecture at risk."

"This position violates Japan's legally binding commitment, turns its back on science, and disrespects the people most vulnerable to climate change," Adow said.

Sivan Kartha, a senior scientist at the Stockholm Environment Institute, said the Protocol is the only instrument that ensures the emission cuts required by science could happen.

"For the Japanese government to walk away from that agreement -- risking its collapse -- would leave us with no guarantee that emissions will be reduced," he told reporters.