This time around, a resurgent dollar is hammering crude futures and other commodities on speculation that Britain could vote to end its EU membership.

The dollar hit two-week highs, then eased back on the sterling's strength as Britain suspended campaigning over its EU membership status after a deadly attack on a Member of Parliament.

Oil pared losses as the sterling rose, but crude tumbled again in post-settlement trade to reach new lows on the day.

Brent crude futures' front-month contact settled down $1.78, or 3.6%, at $47.19 per barrel. In post-settlement trade, it fell to as low as $46.94, its lowest since 12 May.

Brent has lost about $5 a barrel, or around 10%, over the past six sessions. Prior to that, it hit an eight-month high of nearly $53 on supply disruptions out of Nigeria and Canada.

The front-month in US West Texas Intermediate (WTI) crude futures settled down $1.80, or 3.8%, at $46.21 a barrel. It got to a 13 May low of $45.91 after the close.

Drawdowns in US crude inventories over the past month have not provided much support to oil with investors focused more on a possible rise in production as Brent and WTI traded above $50 a barrel each. US energy firms added rigs drilling for oil for a second week in a row last week.

"While oil is obviously getting swept up in the bearish tide of declining equities, falling bond yields and firming dollar, we also see a gradual turn in global oil balances more conducive toward $45 crude than levels above $50," said Jim Ritterbusch of Chicago-based oil markets consultancy Ritterbusch & Associates.

The Energy Information Administration said on Wednesday domestic crude inventories fell 933,000 barrels last week, less than half the 2.3-million-barrel decrease forecast.

On Thursday, market intelligence firm Genscape reported a weekly decline of 76,317 barrels in stockpiles at the Cushing, Oklahoma delivery point for WTI futures, traders who saw the data said. In the previous week, Genscape reported a drawdown of 299,058 barrels at Cushing.