WASHINGTON (Reuters) - The Obama administration's working group this week will discuss rising gasoline prices as it investigates possible fraud and manipulation in the energy markets, Attorney General Eric Holder said on Thursday.

The working group will hold a conference call on Thursday and will meet by the end of the week, he told a Senate appropriations subcommittee.

"The work of that group has been ongoing and looking to see if there are inappropriate manipulations of the market," Holder said. "The FTC (Federal Trade Commission) is also working in this area ... but I understand they're working on a report of some sort that we should be seeing, I believe, relatively soon."

Almost a year ago as gas prices were soaring, the Obama administration created the oil and gas working group, but there has been little released about its work, activities or any findings.

A Republican member of the FTC, Thomas Rosch, complained earlier this week that the working group has "done nothing but sit on its hands."

The working group includes representatives from the Commodity Futures Trading Commission, the FTC, the Federal Reserve Board, Securities and Exchange Commission and the Departments of Agriculture, Energy, Justice and Treasury.

Gasoline prices have jumped nearly 30 cents over the past month and now average $3.77 a gallon, according to data released on Monday by the American Automobile Association, sparking new calls for action by the Obama administration.

(Reporting by Jeremy Pelofsky with additional reporting by Christopher Doering; Editing by Dale Hudson and Lisa Shumaker)