Oil prices have risen 5% due to the Israeli offensive in Gaza and a gas dispute between Russia and Ukraine.
Prices are up by more than 30% since the end of December.
US crude gained $US2.47 per barrel on Monday to settle at $US48.81 a barrel after touching a three-week high of $US49.28. London Brent rose $US2.40 to $US49.31 per barrel.
Oil prices have risen from around $US35 per barrel since Israel attacked Gaza on 27 December, heightening fears for crude supplies from the Middle East.
However, the fighting in Gaza does not directly threaten any oil production.
Russian natural gas supplies to southeast Europe have been reduced as a result of a dispute with Ukraine over gas prices, which began on New Year's Day. Each blames the other for the dispute.
European energy companies receive about a fifth of their gas via pipelines through Ukraine. Supplies were disrupted by a similar dispute three years ago.
Members of the Organisation of Petroleum Exporting Countries agreed last month to cut their production by a further 2.2 million barrels per day in January.
This will bring total cuts by OPEC since September to 4.2 million bpd.
Oil prices previously reached a record $US147.27 per barrel on 11 July last year.