The head of OPEC has urged members of the oil cartel to reject any deal at UN climate talks in Dubai that "targets" fossil fuels instead of emissions, according to a letter seen Friday by AFP.

In the letter sent Wednesday, OPEC Secretary General Haitham Al Ghais said he was writing "with a sense of utmost urgency" as "the undue and disproportionate pressure against fossil fuels may reach a tipping point with irreversible consequences".