OPEC+ will hold its meeting on Oct 5 in person in Vienna, said an OPEC source.
A virtual option will also be available for some delegations due to the short notice if they are unable to.
OPEC+, which combines OPEC countries with allies such as Russia, is meeting against a backdrop of falling prices from multi-year highs hit in March and severe market volatility.
Sources said talks on an oil output cut are focusing on a potential reduction of 500,000 barrels per day to 1 million bpd to support the market.
Earlier this week, a source familiar with Russian thinking said Moscow could suggest a cut of up to 1 million bpd, while an OPEC source put the likely figure closer to 500,000 bpd. Talks are expected to continue ahead of the meeting.