Oil prices ended little changed on Monday on thin volatile trade as dealers eyed increased Japanese fuel imports after a devastating earthquake and wider Middle East unrest.

Oil drew some support from news that Saudi Arabia sent troops into Bahrain to help respond to protests but trade was overall muted by the myriad uncertainties facing the market. Trading volume was the lowest since the first day of the year.

Brent crude futures for April delivery fell 17 cents to settle at $113.67 a barrel, bouncing after sliding to $111.16, lowest since February 25.

U.S. crude futures for April delivery rose 3 cents to settle at $101.19 a barrel, recovering from $98.47, the lowest intraday price since March 1.

Total U.S. crude trading volume was 512,688, the lowest volume since the first trading day of the year, according to preliminary Reuters data.

Traders reexamined the likely fallout from the earthquake and tsunami that struck Japan, looking beyond the short-term reduction in economic activity that originally knocked oil prices lower toward a pick-up in fuel imports .

Heating oil rose 1 percent largely on expectations that Japan will be requiring a substantial amount of distillate or fuel oil to replace lost refinery production and to provide feedstock for electricity generation, Jim Ritterbusch, president at Ritterbusch & Associates, said in a note.

A range of analysts said total crude and oil product imports could rise by 200,000 bpd or more after the closure of a fifth of Japan's nuclear power plants and nearly a third of its refining capacity.

U.S. Gulf Coast jet fuel and ultra-low sulfur diesel differentials to the benchmark heating oil futures contract rose more than a penny per gallon on the expected boost of exports to Japan.

MIDDLE EAST UNREST

About 1,000 Saudi soldiers entered Bahrain, according to a Saudi official source. Opponents of the Sunni ruling family in Bahrain called the move a declaration of war.

The United States does not consider the Saudi entry into Bahrain an invasion, the White House said.

Saudi troops in Bahrain and fighting in Yemen and Libya bounced crude off their lows, said Phil Flynn, analyst at PFGBest Research in Chicago.

Scattered clashes broke out across Saudi neighbor Yemen, as military forces were deployed to check nationwide protests demanding the resignation of President Ali Abdullah Saleh.

Muammar Gaddafi's troops made advances in their counter-offensive against rebel fighters and were outpacing diplomatic efforts to impose a no-fly zone.

Libya's National Oil Corporation (NOC) has called on employees to return to work is hopeful oil production can soon increase, the head of NOC told Reuters.

More than half of Libya's 1.6 million barrels per day oil output is believed to have been shut in because of the Libyan uprising.

JAPAN'S NUCLEAR WOES

Wall Street fell on Monday as traders focused on the implications a possible meltdown at a stricken nuclear plant after a hydrogen explosion at one reactor and exposure of fuel rods at another. All three units are likely to be mothballed after flooding them with seawater.

Japan called on the United States for more equipment to cool down reactors damaged and U.S. officials said the government was ramping up assistance to help Japan avert a major nuclear meltdown, as Washington wrestled with the risks of radiation exposure to aid workers.

(Additional reporting by Robert Gibbons and Gene Ramos in New York, Ikuko Kurahone in London and Alejandro Barbajosa in Singapore; Editing by Marguerita Choy and Sofina Mirza-Reid)

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