LONDON (Bloomberg) -- OPEC will cut supplies by about 5 percent this month as the group implements production constraints announced in December, according to preliminary estimates from consultant PetroLogistics Ltd.

Oil supply from 11 members of the Organization of Petroleum Exporting Countries subject to quotas will average 26.15 million barrels a day in January, down from 27.65 million barrels a day, Conrad Gerber, the founder of PetroLogistics, said on Friday by telephone from Geneva. From this month, members have a production quota of 24.845 million barrels a day. Iraq has no quota.
Saudi Arabia, the group’s largest member, led the cuts, lowering supply to 8.05 million barrels a day in January from 8.6 million a day last month, Gerber said. The kingdom’s new total is in line with its Jan. 1 quota.
OPEC, responsible for about 41 percent of the world’s oil, agreed a record supply reduction at its last meeting on Dec. 17 as demand and prices collapsed. Crude futures traded around $43 a barrel in New York on Friday, having lost more than $100 a barrel from an all-time high reached in July.
Iran reduced supplies to 3.83 million barrels a day this month from 3.85 million a day in December. Nigeria cut to 1.76 million barrels a day from 2.02 million. Venezuela lowered output to 1.97 million barrels a day from 2.22 million, and Angola trimmed to 1.84 million a day from 1.88 million, according to PetroLogistics.