NEW YORK (AP) — Oil resumed its climb on Friday after fluctuating this week amid uncertainty about how much higher it could go.

Oil, which has been rising slowly since 2009, gained momentum as the Libyan rebellion effectively shut down its exports. Crude has jumped 28 percent since the uprising began in the middle of February.

Benchmark West Texas Intermediate crude for May delivery rose US$1.55 to settle at US$109.66 per barrel on the New York Mercantile Exchange. At one point it rose to US$110.10.

In London, Brent crude added US$1.45 to settle at US$123.45 per barrel on the ICE Futures exchange.

Some traders and analysts expect oil to keep rising this year, arguing that the Libyan crisis will continue to constrict world supplies. Libya provided less than 2 percent of global demand. The world may still enjoy a surplus of crude, but experts say OPEC would struggle to keep up with demand if another conflict hampers oil production elsewhere.

Others point to retail surveys and industry reports that suggest Americans have started to buy less fuel, which could bring down the price.

“The biggest problem is that the data is not that reliable in the short term,” said Michael Lynch, president of Strategic Energy & Economic Research. “And when you’re in a bull market like this, people will talk themselves out of negative news. They’ll say any drop in demand is an aberration: People aren’t burning their SUVs just yet, and the economy hasn’t collapsed.”

Experts say crude could remain in a holding pattern while the market awaits further evidence about how consumers are handling higher prices.

This week, benchmark crude has mostly moved against the dollar. Oil, which is traded in dollars, tends to rise when the dollar weakens and makes crude barrels cheaper for investors holding foreign currency. It tends to fall when the greenback moves in the opposite direction.

The dollar was mixed against other currencies Friday after U.S. economic reports showed very modest inflation and an increase in factory production.

In other Nymex trading for May contracts, heating oil rose 3.52 cents to settle at US$3.2242 per gallon and gasoline gained 5.45 cents to settle at US$3.2892 per gallon. Natural gas gave up 0.8 cent to settle at US$4.204 per 1,000 cubic feet.