The Commodity Futures Trading Commission, the government agency responsible for overseeing the trading of energy contracts, has taken the unusual step of revealing a six-month investigation into possible price manipulation.

The announcement comes amid a breathtaking spike in oil prices and growing speculation that speculators are a big cause of consumer misery.

"All Americans are significantly affected by high energy priceswhether it's paying more at the pump, or higher costs for farmers and entrepreneurs," said CFTC Acting Chairman Walt Lukken. "The Commission is taking important steps to ensure that the U.S. energy futures markets function properly and operate free from manipulation and abuse. With these initiatives, we are improving our oversight capabilities and bringing greater sunshine to these markets."

Prices on the oil futures market have surged 32 percent this year and have increased fourfold in the last five years.

On Thursday, oil futures fell more than $4 a barrel to $126.62 on the New York Mercantile Exchange, after topping $130 a barrel earlier in May. Gasoline prices at the pump have reached a national average of $3.95 a gallon, up from about $3.20 a gallon a year ago. In a number of states, the average price has exceeded $4 a gallon.

In a statement, the CFTC said the recent dramatic increases in the price of crude oil traded on futures exchanges make its investigation even more important. It said new measures to promote transparency would improve oversight of the energy futures markets to ensure they reflect fundamental economic forces of supply and demand, free of manipulation and fraud.

Among the new measure is an agreement with the United Kingdom Financial Services Authority (FSA) and ICE Futures Europe for expanded information-sharing for surveillance of energy commodity contracts with U.S. delivery points, including the West Texas Intermediate crude oil futures contracts that trade on both the New York Mercantile Exchange and ICE Futures Europe in London.

While the ICE Futures Europe WTI contract is a cash-settled contract that does not require physical delivery of oil in the U.S., its price is linked to the settlement price of the NYMEX crude oil contract.

"The CFTC currently conducts surveillance of the crude oil markets, in part, using detailed trading data provided by the FSA pursuant to a 2006 information-sharing pact," Lukken said. "The agreement announced today will enhance the amount and quality of the information the CFTC receives regarding crude oil trading in the UK and will enhance the agency's already vigorous surveillance activity."

CFTC says last December its Division of Enforcement launched a nationwide crude oil investigation into practices surrounding the purchase, transportation, storage, and trading of crude oil and related derivative contracts. Although the commission ordinarily conducts enforcement investigations on a confidential basis, it said it is taking the extraordinary step of disclosing this investigation because of today's unprecedented market conditions. The specifics of the ongoing investigation remain confidential.

"In addition to the CFTC's ongoing examination of the role of fundamental economic forces and new investors in the recent commodity market price increases, the agency continues to pursue one of its primary missions to deter, detect, and punish futures market manipulation," Lukkens said.

Critics complain that CFTC has been slow to act. Industry insiders and some members of Congress have warned since 2006 that oil traders were gaining too much influence over the world market price. Rep. John Dingell (D-MI) says CFTC's actions may be too little too late.

"For too long, C.F.T.C. has been operating in the dark," Dingell told The New York Times.

While Dingell points to loopholes that he says allow distortions in the energy market, the commission says it would be hasty to jump to conclusions until the investigation has been completed. In recent testimony to Congress, the agency's chief economist, Jeffrey Harris, attributed most of oil's meteoric rise to other factors, including a supply and demand imbalance, as well as a weak U.S. dollar.