LONDON: OPEC gathers in Vienna this week for a ministerial meeting to decide on the cartel's oil production ceiling, as a predicted drop in demand risks weighing on high crude prices despite Middle East unrest.

The Organization of Petroleum Exporting Countries, which pumps out 35 per cent of the world's oil, may also finally decide on a new head after a vote to appoint a successor to OPEC Secretary-General Abdullah El-Badri was postponed in June.

The 12-nation cartel, which includes the world's biggest oil exporter Saudi Arabia and Iran - currently under an oil embargo - was to hold a regular output meeting at OPEC's headquarters in the Austrian capital on Wednesday.

“OPEC's official production target is unlikely to change at the December meeting,” noted Jason Schenker of Prestige Economics research group.

“Nevertheless, there is likely to be a heated debate over who will be OPEC's next secretary-general.”At its last meeting in June, OPEC opted to keep its oil output ceiling at 30 million barrels per day (mbpd) - after agreeing on the level a year ago - and vowed to eliminate over-production.

But the International Energy Agency watchdog said OPEC has failed to rein in excess supplies, estimating that it had pumped 31.16 mbpd in October despite a sharp drop in output by Iran, which has been under a Western ban of its oil exports since July over the Islamic Republic's disputed nuclear programme.

Despite the over-production caused largely by Saudi Arabia, “no change to production policy is likely in view of the high prices,” said Commerzbank commodities analyst Carsten Fritsch.

Benchmark Brent crude oil futures have traded around $110 a barrel over the past six weeks, above the $100-level deemed acceptable by OPEC kingpin Saudi Arabia.

The Centre for Global Energy Studies (CGES) warned that member countries would however “need to be vigilant in the coming months and to act swiftly in response to a weakening market, if they wish to prevent oil prices from falling much below their unofficial $100 per barrel target.”Despite geopolitical tensions across the oil-rich Middle East, amid also violence in Syria and recent Israel-Gaza unrest, analysts said prices could drop in 2013 should Western economic recovery falter.

“The important thing is the outlook... and most analysts expect OPEC to cut its production” next year because of weak demand growth, CGES analyst Manouchehr Takin told AFP.

Occupying its dozen members' minds this week would also be who should replace El-Badri, who is due to retire at the end of this year after six years as secretary-general, or administrative head of the cartel.

Ecuador's Natural Resources Minister Wilson Pastor last week pulled out of the race to fill the Libyan's shoes, claiming that his move was aimed at enabling greater unity among OPEC's members.

That left three candidates in the running, with many analysts viewing Iraq's Thamir Ghadhban as the best placed, ahead of people put forward by Saudi Arabia and Iran - OPEC's biggest two oil producers.

With Saudi and Iran traditionally holding opposing political positions, experts said the pair could cancel each other out.

Any candidate for the job of secretary-general needs unanimous support from the cartel's members.