The crude-oil output by the Organization of Petroleum Exporting Countries (OPEC) fell in September, as member-nations Saudi Arabia and Nigeria voluntarily decreased production.

Total output in September registered only 27.24 million barrels a day, as against 27.31 million in August.

Pushed by low domestic demand, Saudi Arabia, the largest producer among the 11-member oil producing OPEC nations, extracted only 9.59 million barrels a day in September, a 1.3 percent fall from the previous month, OPEC said in a report.

"Given the decline in oil use by the industrial sector, Saudi oil demand was slightly weaker this summer," OPEC said.

It was in 2008 when OPEC last made its' biggest-ever oil supply reductions. Total crude-oil production that time recorded only 24.845 million barrels a day for all members except Iraq.

But those voluntary crude-oil output slash grew to 43 percent in September from an adjusted 41 percent in August, Bloomberg said based on own calculations. Compliance percentages are based on combined output from the 11 members from a base rate of 29.045 million barrels in September 2008.

The group's members are Algeria, Angola, Ecuador, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, the United Arab Emirates and Venezuela.