WASHINGTON (Dow Jones)-Recognizing new restrictions on energy trading are coming, executives at two major exchanges said Tuesday they are willing to accept tougher regulations despite doubts that speculators adversely affect market prices.

In testimony before the Commodity Futures Trading Commission, CME Group Inc. (CME) Chief Executive Craig Donohue said his company is "prepared to lead" and take steps to allay concerns that big banks and hedge funds are engaging in excessive speculation.

"We are prepared to respond to those concerns by adopting a hard limit regime for those products," Donohue said.

IntercontinentalExchange Inc. (ICE) Chief Executive Jeffrey Sprecher also expressed support for new limits, and he testified that regulators - not exchanges - should be the ones to set them.

Sprecher said regulators should "give users a bucket of position limits they are allowed to hold" so they can shop for the best exchange.

The positions taken by the exchanges is aligned with a shift at the CFTC on energy speculation that coincided with the change from a Republican to Democratic presidential administration. The CFTC was criticized last year for lax regulation after oil futures prices rose to $145 a barrel.

Critics blamed index traders like pension funds and hedge funds for driving up prices, arguing those market players should be subjected to stricter trading limits.

CFTC Chairman Gary Gensler, appointed by President Barack Obama, has said he believes speculation did play a role in driving oil prices to record highs. He indicated Tuesday the agency is headed in the direction of more regulation for the energy markets.

"I believe we must seriously consider setting strict position limits in the energy markets," Gensler said. He added that the "CFTC is in the best position" to apply those limits - suggesting the exchanges may lose their longstanding ability to set limits on energy and possibly other commodities.

"Hedge exemptions from speculative position limits generally should only be available to persons who produce, process, merchandise, manufacture or consume a commodity," said Ben Hirst, the senior vice president and general counsel for Delta Airlines.

Still, exchanges on Tuesday defended index traders, saying they bring needed liquidity to the market, and they reiterated they have not seen one study proving excessive speculation caused record price spikes last summer.

Even the CFTC's own economists, in a report last autumn, did not find evidence that speculation was directly to blame. The report studied financial investors that place bets on commodity prices by purchasing futures contracts tied to indexes.

An updated CFTC report with additional data on swap dealers and index traders is expected in August.

"The numbers that will be in that (August) release have not been seen by any of the four commissioners," Gensler said, adding he thinks it would be "inaccurate to report as to what those numbers might say."

Gensler said the commission plans to start issuing reports with data on swap dealers every quarter, with the goal of making such reports monthly. The reports aim to shed new light on the over-the-counter market, which the Obama administration also hopes to bring under federal regulation.

Gensler is asking Congress to give the CFTC new power to set trading limits on some over-the-counter contracts.

-By Sarah N. Lynch, Dow Jones Newswires; 202-862-6634; sarah.lynch@dowjones.com

(Brian Baskin contributed to this report.)