The West Texas Intermediate for January delivery settled 18 cents lower at 59.02 U.S. dollars a barrel on the New York Mercantile Exchange. Brent crude for February delivery fell 14 cents to close at 64.25 dollars a barrel on the London ICE Futures Exchange.
"A lack of clarity on the path for the group's output beyond 31 March 2020 and the exclusion of condensates from Russia's target calculations partly tempered the bullish sentiment," MarketWatch quoted a note of Amarpreet Singh, oil analyst at Barclays, as saying on Monday.
Oil prices extended big gains on Friday, as OPEC and its allies agreed to steepen production cuts by an additional 500,000 barrels a day, bringing the total cuts to 1.7 million barrels daily,
This additional adjustment would be effective as of Jan. 1, 2020 and is subject to full conformity by every participating country, according to a statement released by OPEC on Friday.
In July, the alliance agreed to extend a production cut of 1.2 million barrels a day for nine months. The pact runs through March 2020.
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