Crude oil prices have increased by 12 percent in the last two days as thousands of refinery workers go on strike, amid a falling US rig count which has signaled lower production down the line.

On Monday, Brent crude was around $55.00 per barrel in IEU, after leaping as high as $55.62 and dipping as low as $51.41, while US light crude traded at around $50.00, after reaching an intraday high of $50.56 dollars.

On Sunday, workers at nine U.S. refineries and chemical plants went on strike in an effort to pressure oil companies to agree to a new national contract.

US crude inventories hit a record high, and any dampening of refinery demand would likely push stocks higher as the slowdown in drilling has still not affected U.S. production, analysts say.

According to crude analysts, the number of operational wells closing in just one week reached around 100, the highest level of about 30 years, and this was another reason of investors demanding crude.