LONDON, May 31 (Reuters) - OPEC+ is working on a complex

deal to be agreed at its meeting on Sunday that will allow the

group to extend some of its deep oil production cuts into 2025,

three sources familiar with OPEC+ discussions said on Thursday.

OPEC+ has made a series of cuts since late 2022 amid

rising output from the United States and other non-members, and

worries over the demand outlook as major economies grapple with

high interest rates to tame inflation.

The Organization of the Petroleum Exporting Countries led by

Saudi Arabia and allies led by Russia, known as OPEC+, is

currently cutting output by a total of 5.86 million barrels per

day, equal to about 5.7% of global demand.

The cuts include 3.66 million bpd by OPEC+ members valid

through to the end of 2024, and 2.2 million bpd of voluntary

cuts by some members which expire at the end of June.

The deal on Sunday could include extending some or all of

the cuts of 3.66 million bpd into 2025 and some or all of the

voluntary cuts of 2.2 million bpd into the third or fourth

quarter of 2024, the three sources said.

"A decision for 2025 is possible," one of them said. "We'll

learn more in the next few days."

The extension of some cuts into 2025 will likely be made

conditional on OPEC+ agreeing new individual member output

capacity figures later in 2024, two of the sources said.

A fourth source, an OPEC+ delegate, when asked on Friday if

Sunday's meeting would make decisions on 2025, said: "Part of

it, yes."

OPEC+ will begin a series of online meetings at 1100 GMT

on Sunday.

The group is trying to agree new oil production capacity for

its member countries by the end of 2024, an issue that has

created tensions in the past because each nation's output target

is calculated based on its notional capacity.

"If the cuts are indeed extended into 2025 that will also

raise the issue of the group's planned capacity audit and

baseline reset, which likely won't be settled until later this

year," said Rory Johnston, founder of oil research service

Commodity Context.

The countries which have made voluntary cuts that are

deeper than those agreed with the wider group are Algeria, Iraq,

Kazakhstan, Kuwait, Oman, Russia, Saudi Arabia and the United

Arab Emirates.

"We would not entirely rule out a plot twist - in the form

of a deeper cut - given (Saudi energy minister) Prince

Abdulaziz's (bin Salman) penchant for Hollywood twist endings,"

said Helima Croft from RBC Capital Markets.

Prince Abdulaziz has repeatedly said he likes keeping the

oil market on its toes and has promised to punish speculators.

The OPEC+ meeting coincides with a sale by Saudi Arabia of a

new stake in state oil giant Aramco.

The Saudi government on Thursday filed papers to sell a

stake that could raise as much as $13.1 billion to help fund

Crown Prince Mohammed bin Salman's plan to diversify the

economy.