By Alex Lawler and Rania El Gamal
VIENNA/DUBAI (Reuters) - OPEC will debate an oil output cut of 4.0-4.5 percent for all of its members except Libya and Nigeria next week but the deal's success hinges on an agreement from Iraq and Iran, which are far from certain to give full backing.
Three OPEC sources told Reuters a gathering of experts from the oil producer group in Vienna had decided on Tuesday to recommend that a ministerial meeting on Nov. 30 debate a proposal from member Algeria to reduce output by that amount.
Such a cut would bring OPEC's current output down by more than 1.2 million barrels per day (bpd), according to Reuters calculations based on the group's October production, and is towards the upper end of market expectations.
But sources also said the representatives of Iran, Iraq and Indonesia had expressed reservations about their level of participation in what would be the group's first supply-limiting deal since 2008.
Brent oil futures traded flat at $49 per barrel, paring earlier gains of around $1 a barrel. As of 1500 GMT, the meeting had yet to end.
In September, the Organization of the Petroleum Exporting Countries agreed to reduce production to between 32.5 million and 33.0 million bpd - an effort to prop up prices - from its latest production estimates of 33.8 million bpd.
OPEC's deal faces potential setbacks from Iraq's call for it to be exempt and from Iran, whose output has been hit by sanctions and who wants to increase supply.
Iraq's foreign minister said on Tuesday in Budapest that OPEC should allow Iraq to continue raising output with no restrictions. [nL8N1DN2FS]
Iran and Iraq raised certain conditions for participating in the deal, according to sources, who were not allowed to speak on the record because experts were meeting behind closed doors.
Sources said Saudi Arabia and its Gulf allies have signalled they were prepared to cut as much as 1 million bpd of their output.
The Algerian proposal would see all member countries, except Nigeria and Libya, cutting 4-4.5 percent from OPEC's estimates of their October production.
OPEC's own estimates, based on so-called "secondary sources", are usually lower than countries' direct submissions to the organisation.
Iran was asked to cut 4.5 percent from a higher ceiling of above 3.92 million bpd, bringing its production under the deal to 3.79 million bpd. That is 90,000 bpd above its October output, according to estimates from OPEC secondary sources.
Iraq was asked to cut about 200,000 bpd. Baghdad is also still debating whether it should cut from the levels of OPEC's estimates or its own, higher, production figures.
"Eighty-five percent of proposed OPEC cuts are from Gulf countries but Iran is still not in favour," one source said.
Non-OPEC producer Russia was also still not agreeing to cut production but favouring a freeze, a senior OPEC delegate said.
"This will make it difficult for OPEC alone to rebalance the market and bring prices up," the source said.
(Editing by Dale Hudson)