The reports come against the backdrop of falling oil prices and months of severe market volatility.
OPEC+ will consider an oil output cut of more than a million barrels per day (bpd) when it meets on October 5, OPEC sources have told Reuters.
Sunday's figure is slightly above estimates for a cut given last week, which ranged between 500,000 bpd and 1 million bpd.
The meeting to consider a reduction in global oil supply is happening at a time when governments around the world are struggling to control runaway inflation. A cut in supply leads to a rise in petroleum prices for consumers.
Wednesday's face-to-face meeting of the 13 OPEC members led by Saudi Arabia and its 10 allied members headed by Russia will be the first in the Austrian capital since the spring of 2020.
"It is a meeting that is taking place at a very interesting global time," one of the sources said.
Saudi Arabia, OPEC’s de facto leader, first flagged the possibility of cuts to correct the market in August.
The cartel had agreed to huge cuts in output in 2020 when the pandemic sent oil prices crashing but began to increase production last year as the market improved.
Now, the output cuts are being considered on the back of a slide in oil prices from multi-year highs reached in March and market volatility.
Oil prices soared to almost $140 a barrel in March after the start of Russia's war in Ukraine, but have since fallen to around $80 per barrel amid recession fears.