* CME has now until Oct. 4 to impose new spec margin rules
* Rules will increase trading costs to spec members
* Unclear if CFTC will ultimately revise rule
NEW YORK, July 24 (Reuters) - The CME Group has been granted a second extension by the U.S. Commodity Futures Trading Commission before imposing controversial new rules that will increase margins for its non-hedge, or spec, members, a CME spokesman said on Tuesday.
CME, the Chicago-based U.S. commodity and futures exchange, now has until Oct. 4 to implement the rules required under new federal legislation, spokesman Damon Leavell said.
The extension is also expected to apply to rival InterContinentalExchange, sources said. ICE declined to comment.
The rules will increase trading costs by as much as a third for exchange members classified as speculators and not bona-fide hedgers such as farmers.
It is unclear whether the 60-day reprieve is aimed at giving the exchange and its members more time to prepare for the changes or if the CFTC may ultimately revise the rule, which is part of the new exchange rules under the Dodd-Frank financial reforms.
Atlanta-based ICE and CME rushed to secure the first extension in May and delay the changes after traders expressed alarm about their financial impact.
In May, the exchanges said they would work with regulators to address member-customer concerns during the review period.
At the time, news of the rule changes caused widespread confusion among metals, energy and agricultural traders and roiled the Chicago Board of Trade corn market as local speculators liquidated spread positions rather than face the need to put more capital on margin to maintain positions.