China and Brazil have criticised the amount of money wealthy countries have pledged to help poorer nations deal with global warming in a sign that sealing a climate treaty next year still faces serious snags.

Speaking on the eve of this week’s UN climate talks in Lima, Peru, top negotiators from both countries said the nearly $10bn that the US, Japan and European countries have promised in recent months was far from the $100bn in annual climate financing that developing nations are expecting from 2020.

The criticisms came as Oxfam said that Brazil should also start channelling money to poorer countries, despite being deemed a developing country by the UN. However, the aid agency – which based its calculations on income distribution, poverty levels and greenhouse gas emissions since 1990 – did not include China.