The crisis has crept up in recent weeks amid wrangling by national fuel marketers over more than $1bn in alleged outstanding payments by the outgoing administration of President Goodluck Jonathan.

Nigeria earns 75% of its budget from oil. The country uses much of that revenue to subsidize fuel prices. Nigerians buy gasoline for just $1.65 a gallon. To the companies that sell fuel to Nigeria, the government pledges to pay the difference between that price and the market rate within 45 days.

Millions of barrels of untapped oil that U.S. shale drillers discovered during the boom years are about to disappear from their inventories.

China's April imports of crude oil from Middle East suppliers rose 10% year on year to a record high of 16.61 million mt or 4.06 million b/d, led by Saudi Arabian supply, according to detailed data released Saturday by the General Administration of Customs.

Prices have also risen with internationally traded Brent recovering from a six-year low near $45 a barrel in January to $64.90 on Wednesday.

Crude oil prices bounced back on Wednesday from steep falls in the previous session as strong Japanese economic growth surprised markets and the business outlook in Australia also seemed to brighten, stoking producer hopes of increased demand.

As the United States raced over the past five years toward becoming a global petroleum powerhouse, the world's biggest oil exporter Saudi Arabia quietly seized a market milestone from America: the largest source of peak summer demand.

Analysts at Moody’s predict that the default rate for oil and gas companies with lower credit ratings — B2 or lower — could increase to 7.4% by March 2016 from 2.7%.

Mexico's government on Thursday slashed its economic growth forecast to between 2.2 to 3.2 percent this year after data showed the economy grew at its slowest pace in over a year undermined by flagging oil revenue and weak U.S. growth.

U.S. oil companies, still smarting from the crude price rout, are attracting a wave of new investment from unlikely sources - hedge funds and private equity firms flocking to the energy market for the first time to bet on a rebound.

Russia is developing non-dollar financing and ties with China in the face of U.S. and EU sanctions

China's land reclamation around reefs in the disputed South China Sea is undermining freedom and stability, and risks provoking tension that could even lead to conflict, U.S. Deputy Secretary of State Antony Blinken told a conference in Jakarta.

The dollar was a contributing factor to oil’s crash between June and January as it rose 16 per cent against a basket of other currencies. However, the 60 per cent decline in crude from about $115 to $45 a barrel over the same period illustrates how crude was largely trading on its own fundamentals, as the US shale boom contributed to oversupply.

More than $100bn of spending on new projects by the world’s energy companies has been slowed, postponed or axed following the oil price plunge, evidence of the drastic industry action that will curb output in coming years.

Sanctions have stopped Russia’s state-controlled oil group Rosneft expanding its trading operations, the company revealed on Tuesday, preventing it from capitalising on one of the main revenue sources tapped by western rivals during the oil price rout.