By Alex Lawler, Olesya Astakhova, Maha El Dahan and Ahmad Ghaddar

LONDON/MOSCOW/DUBAI (Reuters) -OPEC+ oil producers on Thursday agreed to voluntary output cuts totalling about 2.2 million barrels per day (bpd) for early next year led by Saudi Arabia rolling over its current voluntary cut.

Benchmark global oil prices settled down around 2% [O/R], in part because the reductions were voluntary and because of investor expectation ahead of the meeting that additional supply cuts might be deeper.

Saudi Arabia, Russia and other members of OPEC+, who pump more than 40% of the world's oil, met online on Thursday to discuss supply policy.

"The market reaction implies disbelief in the full efficacy of the cuts," JP Morgan analyst Christyan Malek said.

"However, setting a new framework for each member to deliver on its cut reflects the degree of trust and cohesion among the members; case in point, the fact Brazil is joining is testament to the strength in numbers for OPEC+."

The group discussed 2024 output amid forecasts the market faces a potential surplus and as a 1 million barrel per day (bpd) cut by Saudi Arabia was set to end next month.

OPEC+'s output of some 43 million bpd already reflects cuts of about 5 million bpd aimed at supporting prices and stabilising the market.

The total curbs amount to 2.2 million bpd from eight producers, OPEC said in a statement after the meeting. Included in this figure is an extension of the Saudi and Russian voluntary cuts of 1.3 million bpd.

The 900,000 bpd of additional cuts pledged on Thursday, includes 200,000 bpd of fuel export reductions from Russia, with the rest divided among six members.

Russian Deputy Prime Minister Alexander Novak said Russia's voluntary cut would include crude and products.

The UAE said it had agreed to cut output by 163,000 bpd while Iraq said it would cut an extra 220,000 bpd in the first quarter.

Saudi Arabia, Russia, the UAE, Iraq, Kuwait, Kazakhstan and Algeria were among producers who said cuts will be unwound gradually after the first quarter, market conditions permitting.

OPEC+ is focused on lower output with prices down from near $98 in late September and concerns brewing over weaker economic growth in 2024 and expectations of a supply surplus.

The International Energy Agency (IEA) this month forecast a slowdown in 2024 demand growth as "the last phase of the pandemic economic rebound dissipates and as advancing energy efficiency gains, expanding electric vehicle fleets and structural factors reassert themselves."

OPEC+ also invited Brazil, a top 10 producer, to become a member of the group. The country's energy minister said it hoped to join in January.

The OPEC+ meeting coincides with the opening of the United Nations' COP28 climate summit being hosted by OPEC member the United Arab Emirates.