Oil prices hit their lowest in more than three weeks on Thursday, the sixth straight day of losses and longest bearish run since early 2016, as U.S. crude stocks fell less than expected and concerns over Britain's future in the EU weighed.

Brent crude futures, the global benchmark, have slipped 9 percent in just five sessions after touching an eight-month high of nearly $53 a barrel a week ago.

On Thursday, the contract traded as low as $48.14, the weakest since May 24. Prices were down 64 cents at $48.33 by 1030 GMT, set for the longest losing streak in five months.

Front-month U.S. crude futures were trading at $47.39 a barrel, down 62 cents, and reached a one-month low of $47.22 earlier in the session.

"It is mainly risk aversion ahead of the Brexit vote next week so we see some profit-taking on recent long positions ahead of this event," said Hans van Cleef, senior energy economist at ABN Amro in Amsterdam.

With a week to go before Britain votes on whether to leave the European Union, oil and other markets remain in thrall to opinion polls, which are increasingly showing those supporting an exit are in the majority.

European stocks also slid on Thursday after the Bank of Japan refrained from taking further stimulus steps, hours after the U.S. Federal Reserve struck a cautious note on its policy outlook.

The Fed did signal that it still plans two hike rates this year as it expects the U.S. jobs market to strengthen.

Prices also took a bearish signal from weekly U.S. crude stock data on Wednesday showing a smaller-than-expected decline.

Crude inventories fell by 933,000 barrels last week, the U.S. Energy Information Administration reported, less than half the 2.3-million-barrel decrease expected by analysts.-Reuters