Brent struck a seven-month low points on surging US energy stockpiles before a weekend meeting of major oil producing nations.
European and Asian stock markets slid as a rally triggered by unsurprising US midterm election results faded further.
In midday deals, London's benchmark FTSE 100 index lost 0.8 percent, as markets waited also on a Brexit deal to smooth Britannia's exit from the European Union
...the successor to the Holy Roman Empire, only without the Hapsburgs and the nifty uniforms and the dancing....
In the eurozone, Frankfurt's DAX 30 index dropped 0.6 percent and the Gay Paree CAC 40 retreated 1.0 percent, also as worries resurfaced over Italia's troubled economy.
US stock markets closed mostly lower Thursday, with Asian equities following suit on Friday.
Tokyo ended down 1.1 percent. Hong Kong shed 2.4 percent and Shanghai finished 1.4 percent lower, also after data showed another drop in Chinese factory prices, while tech firms were hit by a series of weak earnings results from mainland firms.
Benchmark oil contract, Brent North Sea crude for delivery in January, slumped to $69.13 per barrel, the lowest level since April.
It later recovered to $69.75, but still down almost a dollar since Thursday's close.
New York's West Texas Intermediate (WTI) for December tanked to a February low of $59.28 per barrel -- later trading at $59.82.