Topeka ? A federal agency is investigating transactions involving Westar Energy Inc. and a Louisiana utility that has acknowledged making inappropriate trades of electrical power.

Westar disclosed Thursday it received a subpoena from the Federal Energy Regulatory Commission on Dec. 16. Westar said the subpoena sought details about trades involving Cleco Corp., headquartered in the central Louisiana city of Pineville.

In November, Cleco announced it had discovered questionable transactions involving the company and its affiliates. It also acknowledged making “round trip” transactions, in which a trader buys and sells an energy contract at the same moment for the same price, which can artificially inflate revenue and transaction volumes.

Westar said it was involved in $19.8 million worth of transactions with Cleco over the past three years, generally as an intermediary.

“We will provide full and complete responses to the subpoena,” Westar chief executive officer Jim Haines said in a statement.

Haines said Westar believed its actions did not violate FERC rules, and Westar spokesman Doug Lawrence said FERC told the company the subpoena was “nonpublic.” He also noted a state audit found last month that Westar’s energy trading practices were “in line with industry norms.”

The Kansas Corporation Commission audited Westar’s energy trading activities as part of a review of the utility’s rates. “There were no problems of any substance,” said KCC spokeswoman Rosemary Foreman. As for FERC’s review, she said, “We will be watching this with interest.”

Jim Zakoura, an Overland Park attorney representing large, industrial electric customers, said Westar was trying to downplay the importance of FERC’s investigation.

He said FERC was trying to determine whether such transactions were legitimate trades.

Zakoura said it was possible Westar might have been an intermediary in questionable transactions without knowing much about them.

“What FERC is getting at is to have the integrity of the trading system upheld,” Zakoura said. “It’s certainly a serious investigation, no question about that.”