Oil prices have gone up due to a fall in US dollar and a drop in Nigerian oil production after militant attacks.

Brent crude futures increased 17 cents and traded at $50.72 a barrel, while the US crude oil futures rose 14 cents at $49.83 a barrel, Reuters reported.

Kaname Gokon at brokerage Okato Shoji told the news agency: "With Brent staying above $50, oil is on an upward momentum with the restart of French refineries that were shut on strikes and pipeline attacks in Nigeria."

"Oil is on an upward momentum with the restart of French refineries that were shut on strikes and pipeline attacks in Nigeria."

As part of strikes in France against proposed labour reforms, preliminary work was halted in restarting three of Total’s oil refineries.

According to the French Union of Petroleum Industries, these strikes have added to the energy crisis in country.

Following supply outages in Canada, Venezuela, Libya and Nigeria, crude oil prices have nearly doubled since January this year.

Last week, commercial crude oil inventories in the US fell by 3.5 million barrels, a preliminary poll by Reuters revealed.

Investors are watching for the data to be released by the American Petroleum Institute.