The Commodity Futures Trading Commission is expected today to approve a new regulation designed to enable federal regulators to keep closer tabs on trading on the floors of the nation's commodity exchanges.

The rule, which has been proposed in final form, would require the commodity markets to record the time at which a trade in commodity futures and options is made within one minute of when it occurs.

Under pressure from the exchanges, the commission backed away from its original proposal that the time be stamped mechanically on the slip of paper recording the transaction, as the stock markets have done for many years. Several commodity exchanges had contended during the 10 years since time-stamping first was proposed that an automated recording system was too expensive and too cumbersome for their fast-paced markets.

The rule is designed to prevent what a CFTC spokeswoman called "noncompetitive trading," such as a broker executing his own order ahead of a customer's order, which could make it possible for the broker to take advantage of the customer. It also would allow the CFTC to look for price manipulation occurring within a single day and to make sure traders adhere to limits on speculation.

Currently, trades must be reported within a half-hour window; shortening the time to a minute would let the CFTC and the exchanges themselves follow and reconstruct the course of the market more closely.

"It will allow the commission and the surveillance staff to prove or disprove allegations of illegal trading practices as they occur" if the rule is approved, CFTC spokeswoman Kate Hathaway said.

The securities industry for several years has required automated time reporting within 90 seconds of a trade, although stock market officials said they could not be sure their computerized approach was applicable to the commodities markets.

William Brodsky, president of the Chicago Mercantile Exchange, said comparisons to the securities industry were misleading because of differences between the two kinds of trading systems. Brodsky added he was not satisfied the new rule would keep commodity markets as flexible as they need to be, although his exchange still is studying the regulation.

"We don't think they have moved very far from the original proposal, notwithstanding that they have eliminated the 'Star Wars' aspect" of automated time-reporting, Brodsky said.

Several of the nation's 13 commodity exchanges already have recording procedures that would satisfy the new rule, which lets exchanges choose their own method of compliance subject to approval by the CFTC. The regulation would be effective next Oct. 1, and three months after that the exchanges would have to demonstrate their methods are effective.

Rosemary McFadden, president of the New York Mercantile Exchange, said the system she administers is "99.8 percent" in compliance with the new rule, and could have followed the more stringent regulation proposed earlier as well. Asked if larger exchanges would have more technological difficulty implementing the regulation, she said the New York Merc's trading has grown by between 45 and 50 percent a year for the last three years.