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A stronger dollar and weaker euro also depressed oil after the Bank of Spain said Spain's gross domestic product fell at a "significant rate" in the third quarter.
Greece's transport system ground to a halt, shops pulled down their shutters and hospitals worked on emergency staff on Wednesday as the country's two biggest unions protested against a new round of belt-tightening.
North Sea Brent crude oil futures fell $1.04 to a low of $109.41 before recovering slightly to trade around $109.65 by 0835 GMT. US light crude oil futures also fell sharply, dropping to an intra-day low of $90.33, down $1.04.