WASHINGTON - Federal regulators have signaled a possible shift in policy and may be moving toward setting limits on speculative energy trading.

Speculative trading has been blamed by some for the widening swings in oil prices, especially those of a year ago that resulted in record oil and fuel prices.

The head of the Commodity Futures Trading Commission, which is weighing new restraints, faulted "excessive" speculation but also underscored the role of financial investors in helping to set fair prices that can benefit consumers.

At a hearing organized by the agency last month, Gary Gensler said the futures exchanges have generally not used their authority to limit the size of positions taken by speculative players - something the Chicago Mercantile Exchange expressed willingness to do.

And he cited the Commodity Futures Trading Commission's goal of preventing market power from being concentrated in a small number of powerful financial players.

"I believe we must seriously consider setting strict position limits in the energy markets," Gensler said.

Gensler indicated earlier last month the agency may propose new rules setting limits in the fall. However, he said the agency has opened the debate to determine how new limits could reduce excessive speculation, "not how we can eliminate speculation."

He said the Commodity Futures Trading Commission recognizes the positive role played by the Wall Street firms and other speculators in the futures markets, which enable farmers, oil producers and oil users to hedge their risks and "have a marketplace where prices are determined in a fair and orderly way."

The commission is hearing from consumers, business, traders and financial firms in a series of public hearings as it weighs whether to restrict the amount of trading in energy futures by those who are solely financial investors.

Futures contracts are supposed to reduce price volatility. But speculators use them to bet on market prices, and critics say this magnifies price swings. The volatility in oil prices "is totally unacceptable to the airline industry," testified Ben Hirst, general counsel of Delta Air Lines Inc., who was representing the industry's Air Transport Association.

By law, the Commodity Futures Trading Commission sets limits on the amount of futures contracts in agricultural products that can be held by each market participant to protect the market against manipulation. But for energy commodities - crude oil, heating oil, natural gas, gasoline and other energy products - it is the futures exchanges themselves that set the position limits.

Sen. Bernie Sanders, a Vermont independent, urged the CFTC commissioners to set strict limits on speculative oil trading. Americans are tired, he said, "of being ripped off at the gas pump by the same Wall Street gamblers" that brought the meltdown of financial markets.

Experts and economists are divided on whether speculative trading in the futures markets fans price volatility. Part of the confusion is that "hot" speculative money flows into energy commodities in numerous ways. The commission doesn't track all of them, so it's hard to quantify the impact of speculation.