Updated from 2:28 p.m. EST

Weekend statements that suggested Saudi Arabia wasn't overly concerned with the decline in oil prices put modest pressure on crude futures Monday.

Benchmark contracts for light, sweet crude closed down $1.41 at $54.01 a barrel on the New York Mercantile Exchange. The drop in oil led other energy contracts lower, as well.

Natural gas futures shed 26 cents to $6.92 per million British thermal units. Heating oil lost 4 cents at $1.55 a gallon, as did gasoline to $1.44 a gallon.

"Saudi oil minister Ali al-Naimi seems to be implying that $50 a barrel oil prices are fine with OPEC," says Jason Schenker, an economist at Wachovia in Charlotte, N.C. Press accounts of al-Naimi's statements indicated that Saudi Arabia would be comfortable with "moderate" oil prices.

Although Saudi Arabia is only one member of the OPEC oil cartel, it wields a disproportionate influence on the market because it's the biggest exporter and it sits on huge reserves.

"Ali al-Naimi is the Ben Bernanke of OPEC," says Schenker, meaning that when he speaks people listen.

One factor that could boost prices over the next few sessions is the impact of an OPEC-mandated output reduction of 500,000 barrels a day that's due to start in February. How successful it will ultimately be remains to be seen, as previous cut plans have been at least partially ignored by OPEC member countries.

Milton Ezrati, a senior economist at Lord Abbett, says the recent drop in prices from more than $70 a barrel last summer may be due to the influence of speculators, and he warns of a possible overshoot to the downside.

"Looking forward from this most recent adjustment, there is, of course, a good chance that today's speculative flight from oil could bring prices down even further," he says.

Turning to the oil patch, RBC Capital Markets slashed its target price on oil-field services company Halliburton ( HAL) to $36 a share from $50. Traders marked down prices 1.3%.

Goldman Sachs dinged shares of electricity stock Energy East ( EAS) down to a sell rating from neutral, sending shares 0.4% lower. Wachovia downgraded Berry Petroleum ( BRY) to a market perform rating from outperform. The shares shed 1.8%.

AG Edwards trimmed back its stock price target on Occidental Petroleum ( OXY) to $55 a share from $59. The shares were 0.8% lower.

The U.S. Oil ( USO) exchange-traded fund and the iPath Goldman Sachs Crude Oil Index ( OIL) ETF each lost more than 2.5%.

Major producers Exxon Mobil ( XOM) and BP ( BP) fell, while Chevron ( CVX) edged higher.