Crude oil prices have fallen below $50 per barrel for the first time since 2009, hit by OPEC's production stance, oversupply, weak demand and the strong dollar.

European Brent oil dived to $49.81 a barrel on Wednesday, a 5-year-low. New York crude had already slumped under $50 on Monday.

Oil has dropped about 50 percent since June on worries about weak demand and a decision by the Organisation of the Petroleum Exporting countries (OPEC) not to cut output in response to lower prices.

"The move below $50 shows how momentum is everything here," Michael Hewson, CMC Markets analyst told the AFP news agency.

"With no sign that OPEC will do anything about over-production, it seems likely that we could well see further declines towards $40 in the coming weeks - particularly given that demand shows no signs of picking up.

"Weak growth and weak demand in China and Europe are likely to continue to be the main drivers as the battle for market share intensifies. We'll probably still see sharp swings in the interim but the direction of travel seems clear, unless OPEC acts."

Crude futures had tumbled on Tuesday to fresh multi-year lows in another stormy day for global financial markets, as Saudi Arabia blamed weak global economic growth and said it will stick to its guns on production policy.

OPEC kingpin Saudi Arabia reportedly cut its European and US export prices on Monday, in order to maintain market share.

Analysts said the move was aimed at stifling competition from new market players with higher costs - in particular US shale oil producers.