PARIS — Last week, China was trumpeting its arrival as one of the world’s great economic powers, as the International Monetary Fund elevated the renminbi to the ranks of leading currencies, alongside the dollar, euro, yen and British pound.

This week, China is crying poverty.

A crucial issue at the climate negotiations now taking place in Le Bourget, a northeast suburb of Paris, lies in who will foot the bill for $100 billion a year in long-promised assistance for developing countries, starting in 2020.

Europe and the United States, still feeling the effects of the global financial crisis of 2008 and 2009, have been trying to pass the hat for contributions from increasingly affluent middle-income countries, particularly China.

China has considered itself a developing country for purposes of climate negotiations for more than 20 years. And it is sticking to that position, even as locking in sources for the $100 billion annually for poorer countries is one of the biggest remaining hurdles for the talks, which are scheduled to end Friday.