Benchmark Brent crude hit $50.22 per barrel at one stage on Thursday, its highest level since early November, BBC reports.
The rise followed US data showing that oil inventories had fallen after supply disruptions due to fires in Canada.
Brent crude has now risen 80% since it hit 13-year lows of below $28 a barrel at the start of the year.
US crude oil inventories fell by 4.2 million barrels to 537.1 million barrels in the week to May 20, according to US Department of Energy data.
Canada is the biggest supplier to the US and wildfires in the western provinces have reduced supplies by about a million barrels per day.
Talks in recent months between Opec and Russia about freezing oil production had already encouraged a price rise.
Short-term disruptions to oil supplies have also lifted the price, offsetting higher production from Iran and Saudi Arabia.
As well as the disruption to key oil production facilities in Canada, attacks by militant groups continue to restrict oil pipelines in Nigeria.
Demand has also been better than expected from major economies such as China, India and Russia.