NEW YORK (

TheStreet

) -- Crude oil futures had their biggest single-day loss since July as global debt concerns prompted a rush into the dollar, pressuring commodity prices.

The crude oil March delivery contract lost $3.84, or 5%, to settle at $73.14 a barrel on a day that brought concerns about the weak job market and fragile global recovery to the forefront.

U.S. and European markets spent the day's session under pressure on mounting concerns about how Greece, Portugal and Spain would fund their deficits.

The U.S. dollar strengthened against a basket of currencies, with the dollar index up nearly 0.7%. The greenback's strength diminished the appeal of dollar-priced assets to foreign buyers, causing prices on commodities and related stocks to tumble.

Recovery fears deepened after the Labor Department said

initial jobless claims rose by 8,000 to 480,000 in the final week of January. Economsits had expected initial claims to drop to 454,000, according to consensus estimates.

Although March natural gas fell as much as 3.5% after storage withdrawals were milder than expected, the contract finished the trading session relatively flat at $5.41 per million British thermal units.

Earlier, the Energy Information Administration reported a storage withdrawal of 115 billion cubic feet for the week ended Jan. 29. Analysts polled by Platts had been expecting a withdrawal in the range of 121 billion to 125 billion cubic feet.

The

U.S. Natural Gas Fund

(UNG) - Get Report

ETF closed ahead by a penny, or 0.1%, at $9.83.

The

United States Oil Fund

TST Recommends

(USO) - Get Report

ETF closed off by $1.85, or 4.9%, at $35.80 and the NYSE Arca Oil was down by 3.7%.

The energy sector was one of the day's weakest.

Exxon Mobil

(XOM) - Get Report

lost $1.40, or 2.1%, at $65.20 and

Chevron

(CVX) - Get Report

shed $1.60, or 2.2%, at $71.61.

Europe's second-largest oil company,

Royal Dutch Shell

(RDS.A)

, said fourth-quarter adjusted earnings fell to $2.8 billion from $3.9 billion a year ago and described its outlook for 2010 as "uncertain." The stock slumped 4.1%, to close at $54.42.

Elsewhere in energy markets, the March delivery gasoline contract lost close to 9 cents, or 4.2%, to settle at $1.95 a gallon and March heating oil shed 8 cents, or 4.2%, to finish at $1.94 a gallon.

--Written by Melinda Peer in New York

.