Oil prices slipped back on Monday in thin trading, with markets in London and the United States closed for a holiday.
But prices were underpinned by tensions in oil-producer Libya and by uncertainty over the situation in Ukraine following a presidential election there.
The price of Brent North Sea quality for July delivery fell by 59 cents to $109.95 and a barrel of benchmark WTI light sweet crude for July was down 25 cents at $104.10.
"This amounts to a slight correction in response mainly to election results in Ukraine where voting went relatively calmly and did not lead to big surprises," said Natixis bank raw materials analyst Lysu Paez-Cortez.
She commented that "it is now possible to envisage a return to calm in the east of the country".
Ukraine sits across routes for the export of Russian oil and gas towards Europe, and the situation there remains a matter of concern to traders. A power battle and a tense situation in Libya was also a matter of concern to the market.
"For several weeks, the markets have begun to anticipate the return of Libya but the government's reassertion of control over ports held by rebels has taken longer than expected and recent events have raised new doubts," she said.
On Friday, the price of a barrel of light sweet crude for July delivery had gained 61.0 cents on the New York Mercantile Exchange (Nymex)to $104.35.
In London, a barrel of Brent North Sea oil had closed with a rise of 18 cents to $110.54 on the IntercontinentalExchange (ICE).