The OPEC oil cartel said Saturday there was no "single solution" to the energy transition as pressure grows to agree a phase-out of fossil fuels at the COP28 climate talks.

"There is no single solution or path to achieve a sustainable energy future," said a speech by OPEC secretary general Haitham Al Ghais to the UN meeting in Dubai.

"We need realistic approaches to tackle emissions, ones that enable economic growth, help eradicate poverty and increase resilience at the same time," said the speech read by head of the OPEC research division, Ayed al-Qahtani.

OPEC attracted criticism Saturday after it emerged that the Kuwaiti secretary general wrote to the group's 13 members and 10 allies this week urging them to "proactively reject" any language that "targets" fossil fuels instead of emissions.

Negotiators have held marathon sessions aimed at finding a compromise on the fate of oil, gas and coal as they aim to achieve the global goal of limiting warming to 1.5 degrees Celsius.