Experts expect that Mr Yvo de Boer's successor will be from a developing country. Mr de Boer, who will step down as UNFCCC executive secretary on July 1, is a Dutch national. It is felt that appointing a candidate from a developing country as climate change boss would help bridge the distrust that now exists between the developing and developed countries.

The UNFCCC executive secretary is nominated by the UN secretary-general in consultation with governments and members of UN climate change bureau, which has representatives from each UN region. Support from the United States and the European Union is seen as crucial. Experts say that developed countries may use the appointment to reach out to less developed or vulnerable countries.

In this context, Costa Rica's bid is interesting. Costa Rica, sources said, has sent in the name of its lead negotiator Christiana Figueres for consideration as successor to Mr de Boer. What strengthens Ms Figueres' candidature is the support she enjoys from many members of the AOSIS. She is seen as a strong ally of the small island states both within the G-77 and the broader UNFCCC.

India was the first to throw its hat in the ring, nominating environment secretary Vijai Sharma. Late last month, environment minister Jairam Ramesh said that India had sent in Mr Sharma's name for the UN Secretary General's consideration. Mr Ramesh had also said that China was backing Mr Sharma's candidature.

The South Africans followed suit by putting forward the name of their tourism minister Marthinus van Schalkwyk. Members of the South African government have let it be known that various organisations and countries haven indicated that the former environment minister has the edge in the race.

With both BASIC countries taking their chances, it is likely that some kind of arrangement or understanding will be worked on when the environment ministers of India and South Africa meet in Cape Town for the BASIC meeting at the end of the April.

Indonesia too has expressed its interest in the post. It has put forward the name of former foreign minister Hassan Wirajuda. Their claim is based on the Indonesian minister's key role in ensuring an outcome at Bali in 2007.

In making his choice, UN Secretary General Ban Ki-Moon is expected to keep in mind the need to build trust between the industrialised and developing countries. He would like to avoid a repeat of the situation with Mr de Boer, who was seem to be biased by developing countries, and even the US felt that he was more of an EU representative rather than an unbiased player.