ICE October Brent dipped to its lowest level in a week then settled $2.40 lower at $113.72/barrel Monday, while NYMEX crude also fell as uncertainty over a potential US strike against Syria remained.
In after-hours trade, October Brent fell $3 to $113.12/b.
NYMEX October crude settled $1.01 lower at $109.52/b. October ULSD settled 4.54 cents lower at $3.1183/gal and RBOB was down 5.13 cents at $2.8024/gal.
"The market was bid up last week on fears that something would happen over the weekend with Syria but when nothing did, we saw some profit-taking today," said Gene McGillian, an analyst at Tradition Energy. "The market will continue to keep an eye on the developments and is taking a wait-and-see approach."
Matt Smith, a commodity analyst at Schneider Electric, said the crude complex will continue "to be at the mercy of murmurs, rumors, and headlines relating to Syria, with prices whip-sawing lower [Monday] after whip-sawing higher on Friday."
Smith added that the Qatari oil minister has "hit the wires today to try and assuage the market, saying it is in a 'healthy situation' despite production cuts from countries such as Libya."
Citi Futures Perspective commodity analyst Tim Evans said oil futures retreated from Friday's levels on profit-taking despite stronger-than-expected export data from China that had equity markets higher and the US dollar lower on the day.
Such moves are "normally a bullish combination for oil prices. The retreat is being led by the Brent market, suggesting that the rebound in North Sea oil production following seasonal oil field maintenance and doubts over US political support for a military strike against Syria have prompted selling," Evans said in a note to investors.
US President Barack Obama was seeking to convince Democrats and Republicans in Congress Monday, on their return to Washington from summer recess, to give him a green light to launch military strikes on Syria.
Meanwhile, Russia unveiled a plan for Syria to hand over chemical weapons ahead of a congressional debate in Washington on possible US strikes against the Damascus regime, according to an AFP report.