India's campaign at the crucial climate change talks appeared set for a rocky start with a key negotiator pulling out of the delegation to Copenhagen, apparently upset over the government's announcement of undertaking voluntary carbon intensity cuts.

Former IFS officer Chandrashekhar Dasgupta has not joined the other negotiators who left for Copenhagen last evening to participate in the talks to decide a successor to the Kyoto Protocol to tackle global warming.

A section of the negotiators were unhappy after environment minister Jairam Ramesh announced voluntary carbon intensity reduction to the tune of 20-25% by 2020 in Parliament on Thursday.

Ramesh is later understood to have spoken to the negotiators clarifying that the carbon intensity reduction target was voluntary and not binding.

The negotiating team comprising Shyam Saran, prime ministers' special envoy on climate change, Jai Mathur, head of the Bureau of Energy Efficiency, Vijai Sharma, environment secretary and Prodipto Ghosh, former environment secretary left for Copenhagen last evening.

Dasgupta is expected to meet Ramesh and seek a clarification on India's stand at the climate change talks. There was a feeling among the negotiators that the last minute announcement on carbon intensity cuts could weaken India's bargaining position at the climate change talks.

Analysts believe that India's announcement was made under pressure after China declared that it would undertake a carbon intensity reduction of 40-45% by 2020.

The US had also announced 17% carbon emission cuts ahead of the Copenhagen talks.