OPEC is moving closer towards finalising its first deal this month since 2008 to limit oil output.
Most members are prepared to offer Iran significant flexibility on production volumes, ministers and sources said on Friday.
Iran has been the main stumbling block for such a deal because Tehran wanted exemptions as it tries to regain oil market share after the easing of Western sanctions in January.
Iran’s rival, Saudi Arabia, the biggest producer in the Organisation of Petroleum Exporting Countries, has argued Iran’s output has peaked and it should not be granted major concessions.
On Friday, several OPEC oil ministers, including Saudi Arabia’s Khalid al-Falih, met in Doha on the sidelines of a gas forum.
Iranian officials attended the gathering although Minister Bijan Zanganeh was absent.
At the meeting, OPEC member countries proposed Iran cap its oil output at 3.92 million barrels per day (bpd), a source familiar with the proposal told media.
Iran has previously said it would accept a freeze at between 4.0 and 4.2 million bpd.
Gulf OPEC sources said they wanted Iran to cap output at around 3.6 – 3.7 million bpd – the volume the Islamic Republic is currently producing, according to OPEC estimates.
Iran’s OPEC governor, who attended Friday’s talks, said he was optimistic that the producer group would reach a deal when it gathers formally in Vienna on November 30.
Falih said the Friday meeting went well, but declined further comments.
If OPEC reaches a deal on November 30, it may also draw support from non-OPEC members including Russia, which promised to cooperate, but so far has refrained from any firm commitment.
Russian Energy Minister, Alexander Novak, participated in Friday’s meeting and said he thought OPEC was moving closer to a deal.
If an agreement was reached, Russia was prepared to join and cap output for six months or longer, Novak said.
He also said that more non-OPEC producers could join such a pact.
The Azeri Energy Ministry said on Friday it would send a delegation to consultations in Vienna later this month.