Brent crude for February delivery shed 40 cents to trade under $107 per barrel. The contract had settled 86 cents higher on Friday. U.S. crude fell 92 cents to settle at $91.80 per barrel, after closing $1.06 higher on Friday.
The deal between Iran and six major powers intended to pave the way for a solution to a long standoff over Tehran's nuclear ambitions will come into force on Jan. 20, the Iranian Foreign Ministry and the European Union said on Sunday.
Sanctions against Iran over its nuclear program have kept about 1 million barrels per day of oil off global markets. Some sanctions relief would start on the first day of the six-month agreement's implementation on Jan. 20 and some will be withheld until its final day, senior U.S. officials said.
Still, murmurings of discord rumble under the surface of the deal. U.S. President Barack Obama urged Congress not to impose additional sanctions on Iran, while the ruler of Dubai said the international community should ease sanctions on the Islamic Republic.
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